
I'm not going to call it rape or not rape. But it is not okay to use your partner as an instrument to hurt yourself while they're pleading for you to stop. It doesn't matter that Woowon wasn't thinking of himself when he was asking Seoan to stop. Bottom line, he did not consent to hurting Seoan. Because he, you know, loves him. Of course he doesn't want to hurt him. What Seoan did is messed up and he clearly has work to do on himself.

Baek Yoogun only seems to actually laugh and look happy around Chan (in cat or human form). It's rare but those are the only times he actually seems to be enjoying himself. Chan is also the only one that has shown concern about Baek Yoogun's pleasure during sex (even though he's also definitely been sexually assaulting him but in this webcomic, that's literally everyone)
MC's brother was lied to by his boyfriend and now had to witness that crazy woman's depravity. The boyfriend is a victim but he also agreed to it, even if under duress, and then allowed the woman to bring MC's brother into it, involving him in the kink without consent. I don't think there's any coming back from this for their relationship.