He's a long-lived species, and you're an ordinary human. You used to love each other, but an accident took you away. He thought he'd never see you again, but then, on an expedition, he saw a girl who looked exactly like you.

You can remain an ordinary person or take a long-lived race, it's up to you)

(If there are any mistakes in the text, I apologize, because English is not my native language. )