
I really hate it when the FL is weak and foolish and after the ML showers her with attention ans care, the bitch rebels against him!

I’m not too sure about that.
She’s struggled with suicidal thoughts since childhood because of her condition. I don’t really hate the brother that much — he does seem to regret what he did. But I can’t tell if he’s being sincere or just trying to manipulate the FL so he can drain her powers again.
Either way, her suicidal thoughts weren’t solely the ML’s fault.
Yoon I-gyeong slept with a man. With Cha Seon-ho, his landlord who changes men every week like clockwork. Seon-ho seems to represent non-romance on the surface, casually moving from one affair to the next, yet secretly dreams of romance. Watching Seon-ho exhausted from his one-sided love, I-gyeong began to want something more than just one night with him.
source: Myanimelist