
We know Youngmin was raped. He thinks he wasn't (textually, this was when he was "asking for a friend" with his friend). He was told he coerced the professor to have sex with him. As far as he knows, he cheated on Jungwoo.
Doesn't help that Youngmin's close to having a breakdown (the knives). He feels ostracized from the school because of the rumors, so the thought of losing Jungwoo has made him desperate that he even succumbed to the professor's blackmail.
That's not "slow ass processing". It's called psychological trauma.

You are hundred percent victim blaming. I see you are from US. With what's going on with your political system and how your government is treating rape victims, you dare to say someone should report just like that? And youngmin has a bad reputation around the campus as a sugar baby, who do you think is going to believe him? And his bf isn't rich, the bfs father is.how do you know the parents know and support the relationship? Plz try to think from the victims perspective. And as t8nt3d said, youngmin was made to believe that he consented to the whole thing.
OMFG. U LYING ASS! TELL HIM!!! tbh im aware he was "forced" into the sex but omfg , hes a college student in a modern world with laws against blackmail and with a filthy rich boyfriend. I honestly dont understand why he couldnt report the teacher for raping him. Like, this is the issue with rape, if u don't report it when it happens, wtf is wrong with u?! Ur literally allowing the filthy bastard to roam around and unfortunately one day target someone else. I understand theres A LOT of societal pressure such as if they are ur boss but for one the rapist is a professor, simple employee and did i forget to mention his BF is filthy rich? money = influence. UGHHH this uke has some slow ass processing time for a uni student