I don't understand. In episode 24, Qu Shui finds out that Shang Que and Jie Li wants to kill Xiao Run and she dies in the human realm then immediately goes back to the fairy realm as Dan Yin. When she comes back to the human realm, she remembers that Xiao Run/Chang Heng is going to be killed but Chang Heng also went to the Human Realm so why doesn't he remember Orchid? I hope I make sense.
Edit: I understood now