What is goin on with him?

ok, so my friend zach is actin veeeeery strange lately... ok, so some background info... so we used to be like best friends, and would talk all the time! and then i started to really like him after like 6 months of knowing him. so i told him, and all he said was thanks... so its been almost a year from then, and we had gotten to be even better friends after that... but once i told him that i didn't really like him anymore, he completely stopped talking to me! then even more recently, i finally just told him about how i was almost obsesive about him all those moths ago and how i am over it ( that was like 3 moths ago). and now he ignores me constantly and wont talk to me. he pretend that i am not there, and then sometimes i catch him lookin at me, but i am totally frustrated! i tried to say hi, and i even sreamed his name, and he completely ignored me!! and i said hi to him when he was so close that he touched my arm, but he didn't even look at me!! what is going on?!?!?!