He was so afraid that he was going to lose his lover after accidentally hurting her that he had locked her in his estate for weeks months almost a year he was afraid that she'd leave him after finding out of his Golden Touch after accidentally turning a part of her arm golden he was just trying to keep her with him he became fearful of the idea of her leaving him and he became possessive and obsessive he became a yandere and no matter what he never let her leave his estate