Boyfriend Troubles

Where do I even begin? My boyfriend and I are in love. We've been together for over a year, and I can easily say he's my best friend. I tell him everything and well I tend to complain a lot about my day; how stupid people at school are, that one person that's always on my last nerve, etc. I didn't realize how often I complained until my boyfriend pointed it out and how mad he got because the whole evening I was doing nothing but complaining. So I've been trying to be better, trying not to complain as much, but honestly? It's hard😂 well lately he hasn't been very talkative. He's been bitchy and short with me pretty much for the past week. We hadn't had sex for awhile and we finally did and it was amazing. When we're together everything is great. But it's when we're away from each other that we have trouble talking and  it seems like he just doesn't wanna talk to me. I've told him this and he assures me that he definitely wants to talk to me, but I don't know what's going on. If you actually got this far, thank you for reading. Please give me advice and help me figure out how to handle this situation.