Initially, Di Fuyi planned to spend a good year with her and then let her return to her original body when it was about time for him to fall.
Unfortunately, he did not expect her clone body to encounter a heavenly penalty and turn into a monster that could absorb spiritual power from the people around her. Besides that, the condition seemed to be getting worse; people will start seeing her as a monster as time went by. Thus, it was also harmful to her soul if she continued to stay inside that body and it was possible for her to lose control over her mind as well.