That's exactly it: most people that don't mind NTR DO NOT put themselves into the mind of the MC. I don't mind NTR and do not play as the MC. I control the MC but I am not the MC...and this isn't real. Christine isn't real. Silver isn't real. Etc LOL
Now, those that truly enjoy and seek out NTR, I can't say. It's a kink created in the same random way that you have your own. Maybe they saw mommy fucking the milkman or daddy fucking the babysitter as kids? Who knows and, frankly, it's weird that people care so much.
Most people that don't mind NTR just wanna see new characters get fucked in as most ways as possible. I enjoy this title BECAUSE I can fuck Christine and see her fucked by others. Again, I'm not the MC and none of it is real. We don't care lol