Why does he always want to be around me, make me happy, and hug me, if he doesn't want to go out with me?

My friend Tyler always wants to hang out, go to movies, come over to my house, and stuff like that. When I ask if he'll go out with me he just walks away. He knows I like him a lot, and everyone says he likes me, including his parents(yikes). He gets mad when I talk to other guys if he's not around, and is always texting me. His best friend asked me out and now they aren't friends of course I said no, but why would he care if he doesn't want to date Me?!?!?