As it occured to me, NTR is when the MC watches at others fucking and gets blue balled.
It doesn't seem to be the case here as he can participate and litteraly fuck every female he meets.
Most of it is avoidable, BTW. Even those without included story branching options, simply by pressing the "skip" button and go to the next porn scene. Which is what I do with 90% of any porn scene of every game, considering most are crap, and cringe as fuck. This game is a exception to that. Visually, it's a blast.
Yet, in terms of story and dialogues, it's been litteraly dead for years now. There is nothing new, not a single link appearing between the different plots. No real alchemy. It's there, somewhere, but still a the "teasing/milking" embryonic stage. They'll have to move that schedule up someday, or this game will simply die. But hell. I've not seen that kind of render quality, scene orchestrations and animations anywhere in any other porn game whatsoever.
So to me, NTR is not the issue here. Painting in the angles and playing the clock is starting to be one. Why adding a new character and not developping stories like the one with Lina/Risa for example, or Fiona's garage/ruin side story ? Why not developping really the harem instead of including new characters that won't be developped any further for years ? That's stupid.