Why is my ex being like this? Am I in the wrong?

Have the same question but in the wrong topic.
So, I met my ex in grade 11, we were friends, like, we would give each other advices, I don't know we were good friends. We started dating 4 months ago, but he broke up with me two weeks ago, his reason, I'm gonna put what he said "I'm really sorry but I think I need to not be in a relationship right now. I have so much to focus on; school, work, finding a job, moving. I think it's just the best thing for me right now" so, this is the main thing, I understood because he was leaving after school, and I knew it was not going to last, I know him for 5 years already, he isn't the kind of "distance relationships" guy, but, he started to act like an asshole, he unfollowed me on instagram but kept me on facebook, I texted him that I found his jacket and he took hours to reply "what jacket is it?" Even tho he was connected constantly and when I replied about the jacked he never said anything (I guess he doesn't want it back?). He did it before the break up (taking hours to reply back). I don't know what I did wrong, even when he sent me the text message of why he was breaking up, I sent him some pieces of advice because I still cared for him as a friend, I told him that I understood why and that it was ok, he said thank you and that he would focus on what was best for him and yeah, after that he just started being a total douchebag, treating me like if I was in the wrong. Why is he doing this? It makes me feel like shit.

Just so you know, we never fought, we had no problems in the relationship, we were mature and respectful to each other (until now on his end). In case you were wondering if I was a crazy bitch ex girlfriend, no I wasn't.
Why is my ex being like this? Am I in the wrong?
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