Why are guys such jerks?

there is this guy who ive really com to like. we always talk,text, and were constantly flirting. hes 2 years older than me but he kept saying things like "oh age is just a number" and stuff. once i asked him if i was bothering him and he said "Emily, you're never bothering me." like i meant something to him. Earlier today everyone was teasing me about liking him and i just kept denying it. when i told him about it he found out that i do like him and he said that he doesn't like me and i asked him about the flirting and everything else and he aid "no matter how i talk i don't mean it like that. plus i sorta have a girl..." and i was like "now i feel stupid..." and he said "hey don't worry about it lots of girls like me....." and some other stuff and he was being totally stuck up about it. and i said "you're 2 years older than me, i should have known not to start liking you..." and he said that he has friends that are dating seniors and one that's dating a guy in college (hes a freshman and im in seventh grade) but hes not the kinda guy to do that. and im confused because hes the one that said "age is just a number" and i just want to know why guys are like this? they lead you on and then they break your heart and crumble it into tiny little pieces like its a piece of styrofoam. Im not saying that all guys are jerks but, why did he do this? How can I win him over and get him to like me. I really like him like.... A LOT.