Not sure what you mean. If you play as Marco you see her prostitute herself and get raped from his POV. He's definitely in love with her. Not sure why it's not tagged.
You're almost right. You can enter the yellow circle in the gallery to get a second play-through that's even shorter than the first time. It explains what happened to her at the of the first play-through, and you get an additional h-scene in the gallery once you finish it the second time.
I would agree with you but it can be argued to be as long the player and character feels they are being stolen from, hence the fetish can still be applied. Regardless, let's not be too picky or technical with this, I would MUCH rather have a false positive than a false negative; with a false positive, it is much easier for NTR fans to discover it and judge for themselve while a false negative could mean they will never find it. Also, if mother-son or even brother-sister, where the two have absolutely no such feelings for each other at all, is still considered NTR by so many people, why the heck not this?