user10201: I have recently attended my first Vipassana 10-day course. I observe the moral precepts fully, practice diligently and attempt to proceed wisely on the path. I came into contact with Vipassana because of my ex, who, both in showing me to the path and in harming me, has been my precious teacher. In harming me, in failing to observe the fourth precept and sila, in seeking passion as a distraction from his suffering and a confirmation of his ego, without apparently being aware of this and even if being aware, not changing his behavior, my ex has caused me concern with regard to my own attempts at leading a proper life. I know I am not in a position to help my ex, as he has harmed me (also, I tried and he reacted with hostility), so what I am left with is the striking fact that this amount of delusion is possible in someone who calls himself a serious Vipassana meditator, which worries me with regard to my own practice. If someone who has been practicing for over 10 years thinks they are aware and are everything but, what am I going to do? I have fled into passion as well, in a quest for distraction from suffering as well as from a need for guidance and affirmation of my own ego. 
The obvious answer is to truly feel and accept painful feelings without reacting by fleeing into passion. But these impulses are strong and the mind is clever. What can I do to prevent this behavior? Can there be a mistake in the meditation practice itself that causes such obscurations to persist?
Additionally, I do hope to find a partner who observes truthfulness towards himself and others. How do I go about avoiding the blinding capacities of passion and idealistic desires in judging any such “romantic" situation accurately? I imagine working on one’s own mental and emotional hangups will diminish obscurations — how is one advised to go about this other than meditating? 
I know these are big and difficult questions. Any and all input is appreciated. 

user8157: 
If someone who has been practicing for over 10 years thinks they are aware and are everything but, what am I going to do?

I think this issue you are raising is not really related to Buddhist meditation practices but to the individual. Some individuals, be they Buddhist or non-Buddhist, religious or non-religious, have a keen sense of not harming others & being responsible towards others. Others do not.
That said, about Buddhism, my impression is cultural Buddhism, both Western & Asian, is quite weak in its explanations of sexual misconduct to its lay followers since I get the impression monks don't want to put pressure on people by over-moralising. Therefore, it can be expected that people may practise Buddhist meditation for 10 years but have no real sense of the purpose of the precepts. In fact, there are enough Buddhist teachers that practise sexual misconduct. 
Sexuality is a very strong emotion/drive thus many people struggle to manage it.

The obvious answer is to truly feel and accept painful feelings without reacting by fleeing into passion. But these impulses are
  strong and the mind is clever. What can I do to prevent this behavior?
  Can there be a mistake in the meditation practice itself that causes
  such obscurations to persist?

There are probably many suggestions to this question. One suggestion is to reflect on (think about) what benefit & what harm will come from impulsive fleeing into passion? Will impulsive passion really help yourself? Will it really help the other person involved in the impulsive passion? Or will it create more hurt, more confusion, more regret? Is it really something you really want to do?
Buddhist practises about wise reflection are described in MN 61 and MN 19.

Additionally, I do hope to find a partner who observes truthfulness towards himself and others. How do I go about avoiding the blinding
  capacities of passion and idealistic desires in judging any such
  “romantic" situation accurately?

As has been mentioned by Chris, the teachings in Buddhism about finding the right partner are not based in "romance". Instead, they are based on determining what your life goals & values are and then finding a partner that can fulfil/meet your life goals & values, i.e., a partner that shares your same goals & values. 
This includes things many take for granted, such as having children. There are occasions when two people are together, romantically, for many years and suddenly one person raises their want for children and the other person objects to this. Ideally, the matter of having children should be sorted out before beginning the relationship. 
Thus, Buddhism does not really recommend get "romantically" or sexually involved with a prospective life partner before determining whether that prospective partner is suitable. It may sound very unromantic & clinical but I assume it is like interviewing another person for a job. An employer does not employ a prospective employee until determining & assessing the suitability & qualifications of that person.
Often, this is how traditional cultures operated. Parents would get together & assess whether a partner was suitable for their son & daughter in marriage. The Buddhist approach is similar, i.e., more rational or cerebral rather than "romantic". 
Once "romance" (sex) occurs, that itself starts to make the situation less flexible since two people become attached to each other sexually (with the various demands & expectations) even though they may not be suitable in terms of individual aspirations or temperament.  
Thus, Buddhism encourages the development of 'metta' (friendliness; loving-kindness). We should learn to relate to all people as 'friends' first; putting their welfare first. In meeting a prospective partner, ideally, we put friendship first. We become friends for a significant amount of time before committing to romance. 

I imagine working on one’s own mental and emotional hangups will diminish obscurations — how is one advised to go about this other than
  meditating?

This can be done by learning about & reflecting upon the Buddhist teachings about relationship. By doing this, we can learn about the mistakes we make in our past relationships & the way forward for the future.
For example, if we can see the necessity of the Buddhist qualities prescribed for a suitable partner, we can realise our previous partner never did have the qualities or abilities to fulfill our expectations. But doing this, we may stop blaming them & instead focus on our own choices.  
The main teaching of the Buddha can be read in AN 4.55 however the link already provided explains the main relevant teachings of the Buddha.

user-1: "so what I am left with is the striking fact that this amount of delusion is possible in someone who calls himself a serious Vipassana meditator, which worries me with regard to my own practice. If someone who has been practicing for over 10 years thinks they are aware and are everything but, what am I going to do?"
While this is disheartening indeed, we probably should not measure ourselves against anyone. Consider the following sutta:

[...] From there the Blessed One addressed the bhikkhus, "Bhikkhus, I will teach the method of the forest. Listen and attend carefully, I will teach.
Here, bhikkhus, the bhikkhu abides in a certain forest stretch. When abiding there, unestablished mindfulness does not get established, unconcentrated mind does not concentrate, not destroyed desires do not get destroyed, and the not attained noble end of the yoke is not attained; as for the four requisites of life for the one gone forth, robes, morsel food, dwellings, and requities when ill, are collected with difficulty. That bhikkhu should reflect:
'I abide in this forest stretch, to me abiding in this forest, unestablished mindfulness does not get established, unconcentrated mind does not get concentrated, not destroyed desires do not get destroyed, and the not attained noble end of the yoke is not attained; as for the four requisites of life for the one gone forth, robes, morsel food dwellings, and requisites when ill, are collected with difficulty.' 
Bhikkhus, he should not abide in that stretch of forest, he should leave it by night or by day.
-- MN 17 Vanapattha Sutta - Jungle Thickets

Thus, to evaluate progress, we can reflect on the things like:

does concentration comes easier then before or harder than before?
does unwholesome thoughts come more often or less often?
etc. (can go so far as all the seven enlightenment factors, five hindrances, etc)

The immediate lesson of the sutta above, on the other hand, is that the environment (work, duties, people, food, etc) we find ourselves in may enable or obstruct some aspects of our practice. While someone fully committed to the practice may just take the words above to heart and leave whenever the environment is unsuited, those of us who did not make such commitment might need to find a trade-off.
Another perspective to bring is that the Vinaya orient the sangha members to come forward whenever they transgress. Thus, we should expect people (even the ones we consider to be advanced) to make mistakes.
"But these impulses are strong and the mind is clever. What can I do to prevent this behavior? Can there be a mistake in the meditation practice itself that causes such obscurations to persist?"
Here's a few suttas describing how the Buddha handled these issues in his own mind:

[...] As I abided thus, diligent, ardent and resolute, a thought of [sensual desire, ill will, cruelty] arose in me. I understood thus: 'This thought of [sensual desire, ill will, cruelty] arose in me. This leads to my own affliction, to others affliction, and to the affliction of both; it obstructs wisdom, causes difficulties, and leads away from Nibbāna'. When I considered: 'This leads to my own affliction', it subsided in me; When I considered: 'This leads to others affliction', it subsided in me; When I considered: 'This leads to the affliction of both', it subsided in me; When I considered: 'This obstructs wisdom, causes difficulties, and leads away from Nibbāna', it subsided in me. Whenever a thought of [sensual desire, ill will, cruelty] arose in me, I abandoned it, removed it, did away with it.
Bhikkhus, whatever a bhikkhu  frequently thinks and ponders upon, that will become the inclination of his mind. [...]
But with excessive thinking and pondering I might tire my body, and when the body is tired, the mind becomes strained, and when the mind is strained, it is far from concentration. So I steadied my mind internally, quieted it, brought it to singleness, and concentrated it. Why is that? So my mind should not be strained.
-- Dvedhāvitakka Sutta [Bodhi trans.], MN 19

and:

[...] If, while he is examining the danger in those thoughts, there still arise in him evil unwholesome thoughts connected with desire, with hate, with delusion, then he should try to forget those thoughts and should not give attention to them. When he tries to forget those thoughts and does not give attention to them, then any evil unwholesome thoughts connected with desire, with hate, and with delusion are abandoned in him and subside. With the abandoning of them his mind becomes steadied internally, quieted, brought to singleness, and concentrated. [...]
If, while he is trying to forget those thoughts and is not giving attention to them, there still arise in him evil unwholesome thoughts connected with desire, with hate and with delusion, then he should give attention to stilling the thought-formation(*) of those thoughts. [...]
If while he is giving attention to stilling the thought-formation of those thoughts, there still arise in him evil unwholesome thoughts connected with desire, with hate, and with delusion, then, with his teeth clenched and his tongue pressed against the roof of his mouth, he should beat down, constrain and crush mind with mind(**) (***).
-- Vitakkasanthāna Sutta, [Bodhi Trans.] MN 20

(*) "relaxing of thought-fabrication", per Thanissaro Bhikku
(**) "crush his mind with his awarenes", per Thanissaro Bhikku
(***) "crush unwholesome states of mind with wholesome states of mind", per Majjhima Nikāya Atthakathā

10201: <p>I have recently attended my first Vipassana 10-day course. I observe the moral precepts fully, practice diligently and attempt to proceed wisely on the path. I came into contact with Vipassana because of my ex, who, both in showing me to the path and in harming me, has been my precious teacher. In harming me, in failing to observe the fourth precept and sila, in seeking passion as a distraction from his suffering and a confirmation of his ego, without apparently being aware of this and even if being aware, not changing his behavior, my ex has caused me concern with regard to my own attempts at leading a proper life. I know I am not in a position to help my ex, as he has harmed me (also, I tried and he reacted with hostility), so what I am left with is the striking fact that this amount of delusion is possible in someone who calls himself a serious Vipassana meditator, which worries me with regard to my own practice. If someone who has been practicing for over 10 years thinks they are aware and are everything but, what am I going to do? I have fled into passion as well, in a quest for distraction from suffering as well as from a need for guidance and affirmation of my own ego. 
The obvious answer is to truly feel and accept painful feelings without reacting by fleeing into passion. But these impulses are strong and the mind is clever. What can I do to prevent this behavior? Can there be a mistake in the meditation practice itself that causes such obscurations to persist?</p>

<p>Additionally, I do hope to find a partner who observes truthfulness towards himself and others. How do I go about avoiding the blinding capacities of passion and idealistic desires in judging any such “romantic" situation accurately? I imagine working on one’s own mental and emotional hangups will diminish obscurations — how is one advised to go about this other than meditating? </p>

<p>I know these are big and difficult questions. Any and all input is appreciated. </p>
 8157: <blockquote>
  <p><em>If someone who has been practicing for over 10 years thinks they are aware and are everything but, what am I going to do?</em></p>
</blockquote>

<p>I think this issue you are raising is not really related to Buddhist meditation practices but to the individual. Some individuals, be they Buddhist or non-Buddhist, religious or non-religious, have a keen sense of not harming others &amp; being responsible towards others. Others do not.</p>

<p>That said, about Buddhism, my impression is cultural Buddhism, both Western &amp; Asian, is quite weak in its explanations of sexual misconduct to its lay followers since I get the impression monks don't want to put pressure on people by over-moralising. Therefore, it can be expected that people may practise Buddhist meditation for 10 years but have no real sense of the purpose of the precepts. In fact, there are enough Buddhist teachers that practise sexual misconduct. </p>

<p>Sexuality is a very strong emotion/drive thus many people struggle to manage it.</p>

<blockquote>
  <p><em>The obvious answer is to truly feel and accept painful feelings without reacting by fleeing into passion. But these impulses are
  strong and the mind is clever. What can I do to prevent this behavior?
  Can there be a mistake in the meditation practice itself that causes
  such obscurations to persist?</em></p>
</blockquote>

<p>There are probably many suggestions to this question. One suggestion is to reflect on (think about) what benefit &amp; what harm will come from impulsive fleeing into passion? Will impulsive passion really help yourself? Will it really help the other person involved in the impulsive passion? Or will it create more hurt, more confusion, more regret? Is it really something you really want to do?</p>

<p>Buddhist practises about wise reflection are described in <a href="http://www.accesstoinsight.org/tipitaka/mn/mn.061.than.html" rel="nofollow">MN 61</a> and <a href="https://suttacentral.net/en/mn19" rel="nofollow">MN 19</a>.</p>

<blockquote>
  <p><em>Additionally, I do hope to find a partner who observes truthfulness towards himself and others. How do I go about avoiding the blinding
  capacities of passion and idealistic desires in judging any such
  “romantic" situation accurately?</em></p>
</blockquote>

<p>As has been mentioned by Chris, <a href="https://www.mahidol.ac.th/budsir/Part2_3.htm#13" rel="nofollow">the teachings in Buddhism about finding the right partner</a> are not based in "romance". Instead, they are based on determining what your life goals &amp; values are and then finding a partner that can fulfil/meet your life goals &amp; values, i.e., a partner that shares your same goals &amp; values. </p>

<p>This includes things many take for granted, such as having children. There are occasions when two people are together, romantically, for many years and suddenly one person raises their want for children and the other person objects to this. Ideally, the matter of having children should be sorted out before beginning the relationship. </p>

<p>Thus, Buddhism does not really recommend get "romantically" or sexually involved with a prospective life partner before determining whether that prospective partner is suitable. It may sound very unromantic &amp; clinical but I assume it is like interviewing another person for a job. An employer does not employ a prospective employee until determining &amp; assessing the suitability &amp; qualifications of that person.</p>

<p>Often, this is how traditional cultures operated. Parents would get together &amp; assess whether a partner was suitable for their son &amp; daughter in marriage. The Buddhist approach is similar, i.e., more rational or cerebral rather than "romantic". </p>

<p>Once "romance" (sex) occurs, that itself starts to make the situation less flexible since two people become attached to each other sexually (with the various demands &amp; expectations) even though they may not be suitable in terms of individual aspirations or temperament.  </p>

<p>Thus, Buddhism encourages the development of 'metta' (friendliness; loving-kindness). We should learn to relate to all people as 'friends' first; putting their welfare first. In meeting a prospective partner, ideally, we put friendship first. We become friends for a significant amount of time before committing to romance. </p>

<blockquote>
  <p><em>I imagine working on one’s own mental and emotional hangups will diminish obscurations — how is one advised to go about this other than
  meditating?</em></p>
</blockquote>

<p>This can be done by learning about &amp; reflecting upon the <a href="https://www.mahidol.ac.th/budsir/Part2_3.htm#13" rel="nofollow">Buddhist teachings about relationship</a>. By doing this, we can learn about the mistakes we make in our past relationships &amp; the way forward for the future.</p>

<p>For example, if we can see the necessity of the Buddhist qualities prescribed for a suitable partner, we can realise our previous partner never did have the qualities or abilities to fulfill our expectations. But doing this, we may stop blaming them &amp; instead focus on our own choices.  </p>

<p>The main teaching of the Buddha can be read in <a href="http://www.accesstoinsight.org/tipitaka/an/an04/an04.055.than.html" rel="nofollow">AN 4.55</a> however the <a href="https://www.mahidol.ac.th/budsir/Part2_3.htm#13" rel="nofollow">link</a> already provided explains the main relevant teachings of the Buddha.</p>
 -1: <p><em>"<strong>so what I am left with is the striking fact that this amount of delusion is possible in someone who calls himself a serious Vipassana meditator, which worries me with regard to my own practice. If someone who has been practicing for over 10 years thinks they are aware and are everything but, what am I going to do?</strong>"</em></p>

<p>While this is disheartening indeed, we probably should not measure ourselves against anyone. Consider the following sutta:</p>

<blockquote>
  <p>[...] From there the Blessed One addressed the bhikkhus, "Bhikkhus, I will teach the method of the forest. Listen and attend carefully, I will teach.</p>
  
  <p>Here, bhikkhus, the bhikkhu abides in a certain forest stretch. When abiding there, unestablished mindfulness does not get established, unconcentrated mind does not concentrate, not destroyed desires do not get destroyed, and the not attained noble end of the yoke is not attained; as for the four requisites of life for the one gone forth, robes, morsel food, dwellings, and requities when ill, are collected with difficulty. That bhikkhu should reflect:</p>
  
  <p>'I abide in this forest stretch, to me abiding in this forest, unestablished mindfulness does not get established, unconcentrated mind does not get concentrated, not destroyed desires do not get destroyed, and the not attained noble end of the yoke is not attained; as for the four requisites of life for the one gone forth, robes, morsel food dwellings, and requisites when ill, are collected with difficulty.' </p>
  
  <p>Bhikkhus, he should not abide in that stretch of forest, he should leave it by night or by day.</p>
  
  <p>-- <a href="http://www.buddhasutra.com/files/vanapattha_sutta.htm" rel="nofollow">MN 17</a> Vanapattha Sutta - Jungle Thickets</p>
</blockquote>

<p>Thus, to evaluate progress, we can reflect on the things like:</p>

<ul>
<li>does concentration comes easier then before or harder than before?</li>
<li>does unwholesome thoughts come more often or less often?</li>
<li>etc. (can go so far as all the seven enlightenment factors, five hindrances, etc)</li>
</ul>

<p>The immediate lesson of the sutta above, on the other hand, is that the environment (work, duties, people, food, etc) we find ourselves in may enable or obstruct some aspects of our practice. While someone fully committed to the practice may just take the words above to heart and leave whenever the environment is unsuited, those of us who did not make such commitment might need to find a trade-off.</p>

<p>Another perspective to bring is that the Vinaya orient the sangha members to come forward whenever they transgress. Thus, we should expect people (even the ones we consider to be advanced) to make mistakes.</p>

<p><em>"<strong>But these impulses are strong and the mind is clever. What can I do to prevent this behavior? Can there be a mistake in the meditation practice itself that causes such obscurations to persist?</strong>"</em></p>

<p>Here's a few suttas describing how the Buddha handled these issues in his own mind:</p>

<blockquote>
  <p>[...] As I abided thus, diligent, ardent and resolute, a thought of [sensual desire, ill will, cruelty] arose in me. I understood thus: 'This thought of [sensual desire, ill will, cruelty] arose in me. This leads to my own affliction, to others affliction, and to the affliction of both; it obstructs wisdom, causes difficulties, and leads away from Nibbāna'. When I considered: 'This leads to my own affliction', it subsided in me; When I considered: 'This leads to others affliction', it subsided in me; When I considered: 'This leads to the affliction of both', it subsided in me; When I considered: 'This obstructs wisdom, causes difficulties, and leads away from Nibbāna', it subsided in me. Whenever a thought of [sensual desire, ill will, cruelty] arose in me, I abandoned it, removed it, did away with it.</p>
  
  <p>Bhikkhus, whatever a bhikkhu  frequently thinks and ponders upon, that will become the inclination of his mind. [...]</p>
  
  <p>But with excessive thinking and pondering I might tire my body, and when the body is tired, the mind becomes strained, and when the mind is strained, it is far from concentration. So I steadied my mind internally, quieted it, brought it to singleness, and concentrated it. Why is that? So my mind should not be strained.</p>
  
  <p>-- <em>Dvedhāvitakka Sutta</em> [Bodhi trans.], <a href="http://www.accesstoinsight.org/tipitaka/mn/mn.019.than.html" rel="nofollow">MN 19</a></p>
</blockquote>

<p>and:</p>

<blockquote>
  <p>[...] If, while he is examining the danger in those thoughts, there still arise in him evil unwholesome thoughts connected with desire, with hate, with delusion, then he should try to forget those thoughts and should not give attention to them. When he tries to forget those thoughts and does not give attention to them, then any evil unwholesome thoughts connected with desire, with hate, and with delusion are abandoned in him and subside. With the abandoning of them his mind becomes steadied internally, quieted, brought to singleness, and concentrated. [...]</p>
  
  <p>If, while he is trying to forget those thoughts and is not giving attention to them, there still arise in him evil unwholesome thoughts connected with desire, with hate and with delusion, then he should give attention to stilling the thought-formation(*) of those thoughts. [...]</p>
  
  <p>If while he is giving attention to stilling the thought-formation of those thoughts, there still arise in him evil unwholesome thoughts connected with desire, with hate, and with delusion, then, with his teeth clenched and his tongue pressed against the roof of his mouth, he should beat down, constrain and crush mind with mind(**) (***).</p>
  
  <p>-- <em>Vitakkasanthāna Sutta</em>, [Bodhi Trans.] <a href="http://www.accesstoinsight.org/tipitaka/mn/mn.020.than.html" rel="nofollow">MN 20</a></p>
</blockquote>

<p>(*) "relaxing of thought-fabrication", per Thanissaro Bhikku</p>

<p>(**) "crush his mind with his awarenes", per Thanissaro Bhikku</p>

<p>(***) "crush unwholesome states of mind with wholesome states of mind", per Majjhima Nikāya Atthakathā</p>
