Why does he not talk to me, than all of sudden he does?

okay I dont get this guy?.. one min He’ll be on MSN and he’ll sit there and He’ll talk to me, and be all happy and all that, and than sometimes when hes online he be online and just give me plain answers like meh k… And also… I used to text him and always get a reply back, and now I get nothing, he hasnt been on MSN properly in like 6 weeks, he came on Once, and spoke to me, that was it den went for another 3 weeks and still hasnt came back --.. but I no if I was to text I wouldnt get a text back, its like I’ve done somthing wrong??.. But if I was to text on a different number id get whos this??. You see, I get ingnored on my number.. And than after about 4 weeks he’ll come on MSN and act like everythings Fine :S like Wdf.. I just go along with it because I cant be asked with an arguement.. its like When im at his (because im mates with hes bro).. He wont talk to me.. but when I was at hes work, with he’s brother and he was puting out the work Sign, and it was just me and this lad, he was like soo you okay midgit, and was talkin to me.. And then when hes with his brother, they sit there and call me stuff like other day he was like UVE GOT SAGGY BOOB’S And lucy was like, HOW DO you NO you PERV BEEN looking AT HER BOOBS, And he was like you cann see, and lucy was like no you cant!. Lol and then We was all watchin Family guy, and there was these fat people, and the this guy was liek HA LOOK KATIE’S FAMILYS COMMING UP!. and then he like THERE look and they all laugh --.. and I cant ger a cuss in each ways, because he laughs soo loud and for so long, Really annoying it just not nice.. but I just act like it dont bother me, and than, when me and him, are in he’s house, and he little bro and lucy are in the livingroom he’d kiss me or id kiss him, and everything would be fine --. ( im not with him btw but he knows I’ve fanceyed him for a long time).. And I just dont understand him.. one min its like he Wants to talk to me, and then the next its like I dont care about you bye -- wot do you think he’s problem is?? I hope I made sense