Q:

How to escape new line in man pages

I have refactored a man page's paragraph so that each sentence is it's own line. When rendering with man ./somefile.3 The output is slightly different.
Let me show an example:
This is line 1. This is line 2.

vs.
This is line 1.
This is line 2.

Are rendering like so:
First:
This is line 1. This is line 2.

Second:
This is line 1.  This is line 2.

There is an extra space between the sentences. Note that I have made sure that there is no extra white space. I have more experience with Latex, asciidoc, and markdown and I can control that there, is it possible with troff/groff? I'd like to avoid that if possible. I don't think it should be there.

A:

The troff input standard is to have a newline at the end of each sentence, and to let the typesetter do its job with filling.  (Althought I doubt it was the intent, it does make it play nicer with source control.)  Therefore, it considers sentence ends to be at the end of a line that ends with a period (or ? or !, and optionally followed by ',",*,],),or †). It also believes that sentences should have two spaces between them.  This almost certainly derives from the typography standards at Bell Labs at the time;  It's rather curious that this behavior is not settable through any fill modes.
groff does provide a way to set the "inter-sentence" spacing, with the extended .ss request:

.ss word_space_size [sentence_space_size]
Change the size of a space between words. It takes its units as one
  twelfth of the space width parameter for the current font. Initially
  both the word_space_size and sentence_space_size are 12. In fill mode,
  the values specify the minimum distance.
If two arguments are given to the ss request, the second argument sets
  the sentence space size. If the second argument is not given, sentence
  space size is set to word_space_size. The sentence space size is used
  in two circumstances: If the end of a sentence occurs at the end of a
  line in fill mode, then both an inter-word space and a sentence space
  are added; if two spaces follow the end of a sentence in the middle of
  a line, then the second space is a sentence space. If a second
  argument is never given to the ss request, the behaviour of UNIX troff
  is the same as that exhibited by GNU troff. In GNU troff, as in UNIX
  troff, a sentence should always be followed by either a newline or two
  spaces.

So you can specify that the "sentence space" should be zero-width by making the request 
.ss 12 0

As far as I know, this is a groff extension;  heirloom troff supports it, but older dwb derived versions may not.
Example:
This is line 1. This is line 2.

This is line 1.  This is line 2.

This is line 1.
This is line 2.

SET SENTENCE SPACING

.ss 12 0
This is line 1. This is line 2.

This is line 1.  This is line 2.

This is line 1.
This is line 2.

Results:
$ groff -T ascii spaces.tr  |sed -n -e/./p
This is line 1. This is line 2.
This is line 1.  This is line 2.
This is line 1.  This is line 2.
SET SENTENCE SPACING
This is line 1. This is line 2.
This is line 1. This is line 2.
This is line 1. This is line 2.

