You're right that this game certainly isn't vanilla, that's for sure, and NTR sure has a heavy presence there. But thankfully it can be completely avoided, as it was the devs intention that the player him/herself would choose the course of the story; you could choose to be the loving savior, or you could choose to be an exploiter and corrupt, or just be heartless and cruel and let the family be used as sex toys and even use them yourself, but point being, love route (without NTR) was always one of the paths, even corruption path without NTR was always an option, so basically NTR is only a quarter or a third of the game, think it's just the general setting and atmosphere that makes the presence of NTR seem bigger than what it is, or at least that's my take on it, as it is up to the player after all