I don't think it's fair to group NTR (the girls cheating on you) with you cheating on the girls.
The game already had you railing Yasuka while dating Asami back in version 0.5, long before bad endings were announced. Nobody cared about that then, and nobody seems particularly bothered by the other instances of Saito cheating either.
People absolutely care about the former though, myself included. Nobody wants Saito getting cucked or the girls cheating on him. There isn't any of that in the game, RNGeusEX has already said there won't be NTR, and there's currently no plan to add it.
I understand why people are concerned about the bad endings, because when you hear "bad ending" and start thinking about the worst possible consequences, NTR is obviously going to come to mind. But that doesn't mean it's actually being added.
I do think it's fair to be annoyed that RNGeusEX hasn't been very transparent about what the bad endings will actually involve. My guess is that they want them to be a surprise, especially since there are plenty of people, primarily on Patreon but some here too, who want consequences like these in the game.
Personally, I'd wait until the bad endings are actually implemented before calling the game out for adding cheating/NTR elements. They're happening whether we like them or not, so we might as well judge them based on what they actually are.