No one liked to be schemed against, especially someone of Fu Siye's status.
Previously, he had treated Shangguan Yu as a trusted sister and doted on her, but she had schemed against him and climbed into his bed. She even made her grandfather use the fact that he had saved his life to force him to marry her.
He could not tolerate his life being plotted against and him being forced. Hence, he had never wanted this marriage. He had always wanted her to leave on her own. It had always been bad for her, but now that she wanted to leave, he really did not want it.
He knew that he was being very contradictory, but a person was not a blade of grass or a tree. In the six years of their married life, she was the only one with him. He had long gotten used to her existence, and he could not accept that thought of her belonging to another man and could not tolerate others touching her.