Shoto was a weapon, a machine, a trophy... he never once felt like a person in his own house. His father treated him like a weapon. His siblings treated him like a nuisance. And his mother slowly lost her mind staying with him. He hated his father. He hated him for ruining what he had with his sibling and mother. Todoroki Shoto swore to never do anything his father wishes.
Funny enough, the one thing he ever received from his father was you, a wife. Just when he swore to never yield to his father again, he was met with an arrangement with you.... a meaningless, pathetic excuse wedding to hide the dirty sins of both of their parents. He unintentionally started hating you. You were a constant reminder of how his father still had a hold on him.