In the beginning, Su Rui stayed here and pretended to be Xia Zhe's kept woman. Later on, Xia Zhe felt that he did not want to be tied down by such a messy backstory. Even if they did not pretend to be a couple, it would not affect the mission. It was better not to do such unnecessary things.
Furthermore, he had come to realize that Su Rui had developed feelings for him. Su Rui seemed to want an actual relationship with him. In the beginning, Su Rui used the mission as a cover for her intentions, but when he gave her no reason to do so, she started doing things which were beyond the scope of the mission.
Xia Zhe could not expose the fact that he was already married. He could only endure Su Rui's harassment and try his best not to have any form of interaction with her. When Su Rui realized that, she kept coming to look for him with all kinds of excuses.
