OMG.. i got JEALOUS over a GUY. HELP?

So this guy that i have liked for a good 2 months now was hanging with me and stuff, i was leaning back on him between his legs NOT all the way back or anything like that but because i wasn't comfortable just leaning back on the bleachers. then this girl that is always over him calls him to her and he goes , and leans between her.leaving me alone and stupid feeling cause there was no body else around me then i walk to another side near a different boy and not talk to him the rest of the day.. cause he just dissed me like that... then before that he got spontanously mad at me and started wrapping another boys arm around me and said that he was mad at me, and he didn't even tell me why. plus before that he got angry cause another guy kept um, trying to get fresh with me. then he is always like good with your boyfriend. what is his problem and i can't believe i got JEALOUS over him..