I am almost too scared to ask, but what do you folks consider to be "strong" NTR?
To add on to what others have said:
1. the scenario has to feel realistic or at least plausible in the context of what we know about the characters and the world so far. this disqualifies for me personally a lot of the hypnosis scenarios and a lot of doujins/games where the girl goes from virgin -> slut after one scene.
2. there needs to be significant buildup (or at least enough that i begin to care for the girl). no fun seeing a random girl get NTRed...i need to get an idea of her personality, what she dislikes/likes, how she thinks, etc. a lot of the best ntr titles, if you remove the ntr part, could pass for a pretty decent vanilla.
So with that being said, some examples of strong NTR - CLI Pick's games for RPGM, Mashiraga Aki for doujinshi, H-Mate for manhwa, Boku Gatenkei for VN