Thing about self-inserters is no matter what you're getting NTR'd in porn games and porn in general by your own definition of NTR. You're not the main character. It's all fictional.
I've never quite understood the idea of "self-inserting" into any media in general. I don't need to cut my legs off at the knees, hot glue some hairy feet I got at Hot Topic to those knees, make 3 friends with similar dispositions, find a magical ring that some old wizard dude gets bent out of shape about, and then get forced to travel with like 4 or 5 other guys that are taller than my ass, get separated, nearly munched on by a giant spider, and then nearly get thrown into a volcano just to understand how some little dude feels bout the whole situation.