What is his problem????

ok see this is what i dont get right, me and my friend; broke up a month and two weks now, we talk as ususal when we broke up he is always haring me when he sees me, then we would end up quarelling with each other. this is where the problem is. last week i went over his house to use his computer and it looks like he was in his thing becuase he said he is only going to date girls his age, to add he is 5 years older than me. that all the girls younger than him only want one thing. so this made me start thinking why did i date him. anyways i left and went back two days later; to finish some work and he was all nice to me and i was like why?? because u was acting some kind of way earlier, when i was there he was haring the hell out of me, clowning an making fun of somthing i have on or somthing i wrote, i just ignore him, but why was he actin like an *** when i was around, the day before?.