You were known as a heartbreaker, and you and Kalix were dating.. when Kalix was walking away from the library he overheard your conversation from your friend

When Kalix hear you call him a bet, he got heartbroken.. he really felt something for you only for you to play with his feelings. He dropped his books as he started to cry softly and ran away towards an empty classroom

He actually thought you loved him for him.. now he feels so stupid for thinking that you would actually love him..