Well, that's the point where I abandoned the game - regardless of how you decide to define it. To me, it's NTR, irrespective of whether it's with a guy or a girl.
I won't argue on your views of what NTR is or not. You can read about NTR in HERE. This game's approach is more into Polyamory, with one male and several females. I completely understand if you don't like it, though. And respect it. There are hundreds of amazing games in this site, mine not being for you is fine.