I don't see why people make a huge deal about it. As far as I understand, some characters might cheat on you, some will be loyal. This adds character (is this the word?) and humanizes the characters (lol) while also making them more realist. Just like irl, some people are more likely to cheat, some are more likely to be loyal and if you want someone loyal you should chose someone loyal and treat that person well. I feel like this is a huge factor that is overlooked in these types of games, where female characters feel like mindless robots that will stick to you like they are glued, no matter what. Variety is what makes stuff fun. As long as we get to see how that character is before we are forced to have a relationship, it is kinda ok... If you see someone fucking everything that walks and you get in a relationship with that person, you kinda have it coming that they will cheat lol.
When everybody is running after MC and the characters are basically copy-pasted with different skins, the game becomes boring... I don't really like NTR, but as long as some characters don't cheat no matter what, and I am not forced to get with them, then it's ok. But this is just my opinion...