I believe this is a fundamental misunderstanding of NTR-haters and their psychology.
We find tragedy and negative emotions to be directly counterintuitive to our goals when playing these games. We don't want tragic.
I'm not one of those people that complains when a game isn't made for them, I want everyone to have games they like. However, in the same way that I can't stand people saying things like "Hey, I know you don't like zombie movies, but watch THIS one", I also think you need to understand that you are incorrect. If your game is going to have unavoidable NTR (the kind where the protagonist sees other men fucking girls he's interested in), then you should accept and internalize that you aren't making a game that harem-game lovers are going to have any interest in, and they'll likely be mad if you somehow manage to convince them this game is different... because going by the metric they actually care about, it isn't.