All the guys that I know that don't like NTR don't want to see any LI's with another guy or girl ever. It doesn't matter if it was before they were with them or not.
Amy isn't a LI. She is a side character who is in a relationship with someone else, but you can still have some optional scenes with her if you want.
None of the LIs has scenes with other people. All the LIs have very pure routes that focus on the romantic relationship between the MC and the girl. There are also more corruption-themed routes, but they still focus on the MC and LI. On top of that, there are side characters that you might optionally have sex with or see someone else have sex with, but none of them are in a relationship with you - those scenes often involve seduction, enthrallment, and so on.
Nonetheless, if you're absolutely 100% purist, you probably won't enjoy the game. It's a game about powerful, depraved vampires told from the perspective of a human. You'll see them corrupt, kill, and seduce other people. You will also see vampires that will try to lie to you, seduce you, and manipulate you only for personal gain. Of course, you can resist all of that, always be on top, and focus on a pure relationship with a girl of your choosing, but I don't think that the themes of the game are suitable for people who look for a lighthearted, pure love story. It's a game filled with life-or-death situations where monsters might badly beat you or your companions.
So, I'm not hiding anything or wanting to deceptively lure anyone to play our game. I just say it's not an NTR game. It's not a vanilla love story, either.
It's a love story focused on horror themes.
