Knock him/her out door hitting them on the head with something heavy, tie them down in your basement, and torture them door cutting them and stabbing them until they say they'll marry u and stay with u forever. If not, kill them. They don't deserve to live if they wont love you.
Uhm, befriend him I guess. He must know how kind u really are in order for him to like you. "Like" comes first before "love", even in the dictionary. :)