It always depends. Just having other guys, even in relationships with girls, is not a problem for me. I rather like netorase tbh, it gives me a kick when my MC can take a great woman away from a loser in a game.
I also don't mind potential NTR, as long as through my actions I can prevent it, after all, if it's possible, and I don't manage to stop it, I must have done something wrong. It's like with Babysitter, all the time during development people were crying about how the NTR route was unavoidable and how easy the girls could be taken away, and my MC never was in any danger of that happening, because I made the right choices. And with that I mean choices that make sense, not like everything apart from never letting the girls out of your sight at all times leads to NTR or the choices seem completely unrelated. That stuff I hate.
If it has to happen storywise, I'd rather not see it. I fully accept that there are stories, where another guy bonking a woman the MC is in a relationship with, is part of the game. Where the betrayal is part of the motivation or part of the character arc. I might not like it, but if it is part of something good, I am okay with it. Just, again, I'd rather not see it.
