Honestly I don't see this as NTR as the WrightWorth shippers got to me (My headcanon is that Nick is Bi, or Dahlia ruined relationships for him until Bridge to the Turnabout).
Honestly, the whole NTR debate does have a correct answer that nobody really cares about anymore, and most of the comunity has just taken Occam's razor to the whole concept of NTR to simply mean "Anyone who is not me having sexual relations with potential love interests in these games is NTR" Is that corrrect? No. Is it how the term has essentially been transformed? Yes.
For this game I think the NTR tag relays the message most people are looking for. Does Maya get fucked by someone who is not Phoenix? Yes. It works, people really love the game and the Dev is doing a really solid job. Let's not bother splitting hairs over these issues of loose terms and non-canon shipping. Let's just watch the babes we love getting corrupted in the best way possible.