Ughhh i like this guy....but its such a pain!:/helpp!?

Okay so theres this guy in my 5th & 6th period & he liked me and i started to like him...But he use to allways come and sit next to me and just kinda like cater to me.Was such a sweetheart.And loved it.And now im starting to like him alot but idk why but know hes startin not to pay attention to me in cl he never looks at me anymore and the one time i told him to come sit next to me he didnt. =/ idk?Is it me.. how does he just kinda kut me off?Like he use to be like obbsessed and now its like he doesnt even care?How do get him back?I really like him.