What could be the problem?

My long distance boyfriend is acting strange. For 4 days in row he is moodless or easily get angry at me when we talk. Even asking questions triggers him n these questions are mainly whats wrong with him. I was calm, supportive hoping he can confide himself cuz it was affecting us. We stay on call for hrs without saying anything, if i say something he get pisses off even if its about him being good.

5TH day i confronted him n asked if it was me, work, money, his friends, n he said its nothing of sort. He said i can't help him with it and am useless. So i decided to take a break from him n let him be n me get my peace. He was cool with it n haven't contacted me for 2 days..3rd day he said he missed me n i said ok. Then we didn't talk for another day.

Next day he still acts the same but said it was rough days n he needs time alone. i was very calm n politely told him, ok i understand, and we can have good conversations when want and don't call me if all u r gonna do is insult or give me attitude. We said bye. And he deactivated all his socials after few mins.
What could be the problem?
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