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