Getting accepted to present at a conference, but choosing not to go - including this in SoP I am a masters student who has just had my extended abstract accepted to the largest conference in my field, however, I am faced with a very difficult decision that requires perspective. 

The Problem Context: I have made plans with a long lasting friend of about 12 years to go away together on a trip during a period of the Summer in which the conference that I have been accepted to is also occurring - I made a mixup in the dates which has gotten me into this position in the first place. The likelihood that we will be able to make this trip happen in the future is very slim because he's going to be having children shortly. On the other hand, presenting at this conference (especially as a masters student), would really help to boost my application when applying to doctoral programs.

I think that if I didn't go on this trip, I would regret it, so I am leaning more towards this than the conference. However, I am wondering if it would be worth mentioning in my SoP that I was admitted to the conference - to signal that I have potential - but due to my previous commitments (without being too specific as to what they are), I chose to decline the opportunity to present. 

From the perspective of a graduate admissions committee, I am sure that they would prefer to see on a CV that you attended and presented at the conference. But I wonder if being transparent in the sense that I was accepted and chose to decline presenting at the conference if this could be a net-negative for the application to the schools that I apply for. 

Problem Definition: If I were to decline the opportunity to present at this large conference, but made mention in my SoP that I had the opportunity to do so and chose to decline, would this signal a net-negative to graduate committees? Alternatively, would it be better to not mention that I had the opportunity at all?
It's not unheard of for someone to be unable to attend a conference after having their work accepted. This can happen for any number of reasons that may be seen as having varying levels of validity in someone else's eyes, ranging from "death in the family" to "I have better things to do". I don't see a compelling reason to open yourself up to such value judgments about your reasons for choosing to not go to the conference. Having your work accepted at a conference is an accolade in itself, so it's worth mentioning, but you could simply say that you were "unable to attend" and leave it at that. Your particular reasons for not attending aren't relevant to the point you're making (that your work is good enough to get accepted), and may or may not be viewed unfavorably depending on the individual, so there's not much of a reason to go into the details.