maybe he gets the same feeling as the ML to restore some of his magic or from childhood he wanted her whole attention.
I think it's more likely he's a sadist and just wants to break her after years of "teasing" when growing up together. I mean based on her previous life, he was a really piece of shit and from what we know so far his parents are both trash too.
Like the trash he is he wants what he can't have. She stood up to him when she was young and got his attention. Losers like this get a rush from taking things they want. He is a sadist and wants to see her broken by him. I bet you if she had fawned over him like I'm sure other people do he would have 0 interest.
why he so obsessed with her like why, what's the reason? lol