First, I think this has the makings of a great game. I'm really liking it so far, though it's not perfect of course.
For now, I want to talk a bit about how I view/play Nate's situation. First, I want to say that I'm really glad that, as others have noted, Nate wasn't given a small dick which gets him humiliated by everyone that sees it. I really hate that trope. He does, however, seem to have been excessively timid/disgusted by sex and sexy girls. It's like he's still stuck in the "girls have cooties" phase. This is another trope I'm not keen on, but fortunately it's not as overplayed here as it often is in other games. Still, his lack of initiative or understanding about sex and sexuality makes suspension of disbelief difficult.
To get to my main point, though: I want girls to be happy and enjoy themselves. If being with a single guy in a committed relationship makes them happy, then that's great. If they want to basically be asexual and have platonic relationships with everyone, and that makes them happy, then I'll support them and cherish their friendship. And... if they get off being utterly depraved and wanting to be gangraped, covered with cum, and in a near constant state of perverted lust, then I support that, too. It's their body, their life, their decision.
So, when Erickson starts going on about breeding Nate's Dad's Wife, and she lets herself be drawn into cheating on Andrew, that's her decision. If she gets off on being bred by a alpha male, she's responsible for her decisions -- Nate is not. Also, as the player controlling Nate, I want to see her turn into a slut that I can have Nate fuck. But even if Nate doesn't get to do it himself, seeing her acting like a degenerate cock-sleeve is pretty hot. So long as it is her decision and she's not being blackmailed or emotionally manipulated by Erickson.
With Luna it is much the same, for much the same reasons. The only significant difference is that she's actually Nate's girlfriend, which means Nate has a vested interest in keeping her attention focused on him. It is not, however, in preventing her from turning into a slut, if that's what she comes to want (I am guessing Stepmom was a slut previously when she was at the sorority). But even if she dumps Nate, as long as she is pursuing her course because she wants to, then it's fine.
As for Nate: I have a hard time running away from women that want to and enjoy having sex. Slutty women are turn ons just by being sluts. Also, girls like Claire clearly *want* sex and enjoy it, so why not give it to them? Julie, too, going by the photo she shared of herself with that giant cock. How could I say no to that? Well, Nate, my dude, I can't, which means neither can you.
Anyway, as I said at the beginning, this has been a pretty good game so far, and I'm looking forward to more. I hope we get better ways to make money, because the amounts needed to unlock various scenes is pretty high. I wish the Dev well. Thanks for making the game.