A promise

A young boy who made a promise to a young girl. A girl who falls in love with the boy. Time passes the boy loses his memory and grows up. But for the girl who may never grow up it's not so easy.
Then as time passes they reunite.
Though is that enough to save there love?
Will he remember?
Can she hold on?
Years pass and the boy turns 16. So tell me can he still love a 16 teen year old in a 12 year olds body?
Could you?
Not only that but a girl who is being hunted down. For a strange power she has and for her immortality
Will they survive?
Can they ever be together?
But one of the most important question you should ask is can he keep there promise?
You tell me.