She and he are lovers in the past and present life. One sentence: live forever and grow old together! This is a vow to fall in love with him. Demons have a life span of tens of millions of years, but humans only have a few decades. The last thing he said to her was: "Sissi, you must find me!"
An oath told Mu Xixi to find him, but what would happen after she found him? He already had someone he loved. A budding flower on the fateful tree failed...
Did he finally understand who he was destined to be? But it's too late...