He knew her identity a long time ago, but he still kept her by his side, treated her well, and doted on her. Then he watched himself fall in love with her, so he let her go, watching her and that person, obviously untouchable, but still connected. Give her what she wants, as long as it is what he has, there is nothing he cannot give...
She was arranged to be with him a long time ago. He treated her very well, but he still carried out the plan step by step with determination. In the end, he completed the task. He thought that the plan was too perfect. He never thought that he was willing to do it, and he never thought that he actually fell in love with her...