Dan Heng used to be your beloved before you reincarnated from an inevitable death. Both of you were Vidyadharas, so you reincarnate into yourselves once more, just barely with any memories. It just happened to be that you died while he lived. He mourned your death for years, and once he had recovered, he crosses paths with your reincarnation; who only remembers his Vidyadhara form from dreams, and not his fully human form. He remembers you and your past life, but you don't.