If people faint over something within YOUR game, well, FUCK EM! It's YOUR game, not theirs. If they don't like it, they can make their own fucking game!
Especially since:
1. The "ntr" is an important part of your storyline.
2. Technically, it wasn't even NTR, nor cheating, but voyeurism.
Sorry, but adapting YOUR storyline to remove "ntr" because of a bunch of whiners is in my opinion as bad as adapting YOUR storyline to ADD something like Futa or gay or scat content because a vocal minority of idiots demand you include it. It's YOUR storyline. Do yourself a favor, and stick with it. It will make it much easier for you to make the game you want to make, than to make the game you don't want to make, no matter if you make 8 bucks, 80 bucks or 8,000 bucks a month from it.