Hi, thanks for your comment. I understand that what you're looking for is a story where the protagonist is the only male character present and all the girls are focused solely on him.
I think the meaning of netorare (NTR) is often misunderstood. NTR is a Japanese adult fiction genre (mainly anime and manga) that focuses on infidelity and humiliation, where a third party seduces or "snatches" another person's romantic partner. The protagonist suffers jealousy, deception, and deep emotional misery, and the story isn't exactly a happy one. Those kinds of situations don't exist in this game.
For me, having a girl have had relationships BEFORE meeting the protagonist isn't NTR, since there was no relationship between the protagonist and the girl in question. Each character has their own life, past, and personality, and not all of them have to be virgins or wait until they're 30 for the player to show up. That's part of giving them realism and differentiation.
The focus of the game remains on the player as the center of the experience, and all relationships revolve around them, without deception or betrayal.