No I don't think it is I've sided with the girlfriend every time and she runs off anyway to the host even to the point of doing a blowjob. Clearly she is a very jealous girlfriend but doesn't want to take the time to explain how she feels so she runs off and rides another dude's cock
I think you also need to have a high amount of favorability with the main girl, using constant dates, sex, chat, and aroma diffuser.
Because I pulled the Unlock All Switch, and there IS a happy ending. Though, yeah, I don't think it's NTR avoidable, just bad end avoidable, as you're railroaded towards her cheating at least once on Christmas Eve.
Fucking dumb bitch. The worst part is that her stupidity is believable, it's just that the level of escalation was just too dumb for me to really get invested in because, while somewhat believable, it's still too dumb for my mind to fucking comprehend the stupidity of the girl.