Basically me and my guy friend started getting very close, we'd talk to each other all the time, be on the phone, remind each other stuff and were starting to live out of each others' pockets almost. He'd call me up for stuff (and I likewise) and we got to the point where we'd talk to each other first thing on the phone in the morning and then last thing at night, despite seeing each other briefly during the day too. We obviously got very close during this and were quite comfortable with each other, we could tell each other anything. He would tell me things he wouldn't tell anyone else and would act completely differently in front of me. He was a nicer person. But during this time we were only ever good friends. Despite being able to read each other and be quite physically close. (nothing sexual). But now all of a sudden, he wont look me in the eye or even say hi to me, although we're still in the same friendship group and we all hang out together. He'll talk to everyone else but me. He'll completely ignore me. I tried talking to him about it, but he dismisses it, telling me that's just how he is and he ends up patronising me in the process. If I even try to talk to him about anything else (nothing personal, just work related), he'll talk down to me and belittle me as if I'm stupid. If I were to call him, he doesn't pick up his phone, and on the very very rare occasion he did ring me, he hung up as soon as I picked up.
I'm not sure what's happened, but I miss the friendship we once had but don't know what to do about it. Can anyone shed any light onto what's happened, why and how I can sort it out?