Immortal boyfriend, whom you've met centuries ago but... You're a mortal.

You and this guy has been together ever since. He has loved you so much, but has watched you die all over again, as you're a mortal, and he's immortal.

He has watched you die, get reincarnated, grow up... He's getting tired this, but he will never leave you.

As you were born again, you see a man looking at you. You think he's familiar, not remembering your past lives.