70's/80's romantic film about reincarnation and a girl who was born in heaven, making her an angel?

Is it where the girl was born an angel, her parents both died and met
in heaven, creating her.

Then she gets sent to earth to be a mortal, which isn't supposed to
happen because angels aren't meant to be chosen to do that.

He goes down there to look for her, but forgets what his mission is.

They live their lives and eventually die and meet again in heaven.

But this time they go back to earth together on this bus and they're
born as twins.