Encountering an Immortal: My Partner Comes from the Shan Hai Realm

Can someone explain why the girl he loves can turn in the blink of an eye into a man nearly six foot three, taller, more handsome, and more capable than he is?

And can someone tell him what’s happened to this world? Weren’t we promised a scientific, materialist worldview? Why are all kinds of monsters and demons showing up?

One-line summary: From beginning to end, he’s searching for someone.