Jeez, I don't think anyone here has a real sex life. Sometimes you just want to fuck the girl and you don't care if other guys fuck her too, that's called casual sex. As the dev said in the comments, there are characters that Mc really loves and wouldn't share with anyone and other characters that he doesn't care if other guys fuck them either. Bernice for example has a husband and there are other characters that we/mc don't even know if they have romantic partners or not. I don't think the game will progress to a real NTR because I had already asked him that question and he said that he doesn't plan to put mc in any situation where he becomes a cuckold. Calm down guys.