Some. Nora would be for one, if I have to point a finger at one of them for sake of example. And no, there is no ''round and about''. Main LI's are main li's and they're with Main Char. NTR is not my personal jam, not something I like on my own, thereby I do not meddle in it or bother writing about it. That being said, I'm aware of some planned scenes where main character does sleep with other people's wives, but, as far as my research goes, that isn't considered NTR or does it affect MC in such shape or form. As for "mentioned" in text... doubtful. When doing character backgrounds and their past, their sex life is last on my list if it AT ALL on my list. I don't see reason to narrate through it. Some things I leave to player interpretation. Hope that helps.
Is because many devs have shit like "I used to have lots of sex when I was in college" or such crap cuck tmi's (too much information) dialogue shit when talking to mc or someone else in the vn.
But good to know, as for netori ( fucking someone else's wives, that is fine for us so long the wifes aint fucking their husbands anymore. We ain't want sloppy seconds.)
That's why I asked you before too, Anyways, good luck.