-sigh- ...Why Could He Be Acting Like This?

Alrighty... so one of my best friends is starting to change and not in a good way... it started maybe after an argument (which really was...ok after this: a href="http://answers.yahoo.com/question/index;_ylt=AvzU7TDJheLL0nLmmD2ng6MazKIX;_ylv=3?qid=20090922073911AAgLVBx"http://answers.yahoo.com/question/index;…/a ) but it got resolved with him saying he just wouldn't tell me that anymore -.- kind of dramatic but... -sigh- ok so it seems like he's gotten kind of rude and sarcastic when it doesn't call for it. Examples: my sister sent him a pic of her in negative prospective (reversed colors) and granted it was kinda too bright to see but you could tell it was her. He should have especially because he has a good eye for things but he was like "idk wtf that is" =_= she thought nothing of it but that wasn't...nice... and then i told him something a while ago that i only tell certain people i can trust and that some people wouldn't believe. I had to remind him of it and then he was like "riiiight..." as if he didn't believe me. You wouldn't joke about something like that... it seems to be different since he's with his ex again... i didn't think it was a good idea but i honor his choice but... i don't know, it just seems like he's changed and i don't know why and i'm tired of all this conflict with him...