The game kinda implies that it's not just that that causes them to fall for the guy but yeah, since the part that was seemingly meant to explain that never came out it does make the game fall under that shitty trope.I have no issues with NTR games, I've played many and found some to be enjoyable, but the one trope that gets over used so much is "antagonist rapes girl, girl magically becomes addicted to his dick".
This is another one of those.
As an aside, scenes aren't unlocking in the CG room after I complete them. I've gotten the 2 endings and neither scene unlocks.