Why has been acting like this?

Okay so i have (actually had) a bestfriend (a guy)! I met him through my galfriend! They were going out! But anyway we became best friends and later on him and my galfriend broke up! We we're still good friends he made me feel better when i was sad and we did a lot of stuff together! But latley he's been a total jerk to me!! He used to give me big hugs and now everytime i come up for a hug he just gives me high five with a pound like i'm one of his guy friends! I have to talk to him for him to talk to me and lately he duznt even say anything he just says sup and puts his head back down on the desk! And last week on my way to cl (he had the same cl) he hugged my friend that he didnt even kno and then told me "yeah what do like about that"!! And then the jerk tried to talk to me in cl after that!! Wut is his problem i've always been a good friend to him!