It was never love. It was always about power over her. She is the "most dignified Woman, second only to the mother of the empire" in her own right she was a queen. Oscar is a pathetic inadequate boy. To him he couldn't be inadequate because look at how he can play with the highest ranking Woman 2nd to his mother. If we add in some mommy issues. It can just get worse
If you don’t mind spoilers, the way someone explained it (because I didn’t read the novel, but they did) is, he basically married her to make Carcel suffer. It’s like wanting revenge on someone that makes you feel small, knowing how much they love the person you’re degrading. Since Carcel and Ines were married in their first life and only Oscar remembered that life, he made himself into a man she could love so she’d marry him, then did everything he could to crush her so they would both suffer since Carcel already loved her. The fact that Oscar was also possessive and wanted to exert power over her, exacerbated his vile traits. But somewhere along the way, during his evil doings, he actually fell in love with Ines, so now he’s obsessed with having her back in any way, shape or form.
I really dont get that demon oscar's thought process of abusing and treating inez like shit on their previous life and then now he's all obsess and in love with her. Like dude can't you just like i dont know maybe die bruh.