@deathmailrock: The idea that one should be so bothered by rape in
fiction is ludicrous, to me; then again, we're in the era of "triggers", where fee-fees trump logic and even reality, and the progressive Petri dish Tumblr--though mostly dead--has infected the rest of the West with its cultures upon taking that critical blow. There's possibly a trigger for anything and everything, so you have to walk on eggshells for those liable to be triggered. Especially when reading a manga about paraphilia, where the idea of forced sexuality is regularly explored.
Ah, but those people aren't weak or overly sensitive, don't you
dare even imply such.
Anyway, I found the MC to be absolutely repulsive for the reason you spoke of: this guy has gone farther than what it takes to consider a guy and a girl "romantically involved". He likes Yuki-nee. He wants to make moves on her, and has. Yuki-nee likes him. She wants him to make moves on her, and has made it patently clear that she wants such (if a girl baring her breasts is any indication). That he tolerated this whore (to hell with her name) taking her clothes off in front of him--and even proceeded to play along with her and
wipe her uncovered back as she requested was very obvious infidelity against Yuki-nee; how could anyone think otherwise, she's already said--multiple times--that the only one she wants to do that sort of thing with, or see her in such a lewd state, is the MC. And so he goes on to play the role of "weak female, devoid of agency", letting this girl undo his shirt and even bite him. He stayed there for it. (Before all of this, he did what the whore wanted and started affixing "-nee" to her name solely because the whore insisted he did. Yuki-nee, of course, didn't like it, but MC-kun didn't seem to care.)
Then, after he gets caught, "Are you mad?"