Actually a quite silly and possibly desperate question.

I need some advice.

So, I've been close फ्रेंड्स with this guy, who shall remain unnamed, so let's just call him A, for almost two years now. Admittedly, I once had a crush on him, but it passed fairly quickly. Our connection is very secure and our friendship is very close, as he knows much about me and I him. I recently moved to a new school, and I've been missing him a lot lately. I still keep in contact with my other friend, J, who is best फ्रेंड्स with A. Like a BFF trio या whatever. Anyway, J is extremely sad that I left, it seems, and has sent me e-mails updating me on the latest in my old school. However, he says that A has been अभिनय very... mean. Like he's always angry about something. He's insulted a couple of people I know multiple times, and it's just not like him. This only started happening about a week after I left, around New Year's. I just want to know, do आप all have any hunches as to why his attitude has changed so drastically? And how can I talk to him? If any further details are needed, please ask. I'm just so stumped.

TL;DR: My friend has been angry and a real jerk ever since I left my old school, and I'm wondering how I can talk to him and figure out why.