Love Vs. Prophecy

This is about 2 complicated love stories. One love story is the very complicated one and our main story. Their love is fine at first but because the boy knew a secret from his past and a prophecy that his mother left him to do. But according to the prophecy, he needs to kill his love one for she is very dangerous to everyone.Will he be able to do his prophecy? Or will he just live with his beloved forever?
(for more specific descriptions, please read the Introduction/Prologue)