confusion (ldr)

I'm in a long distance relationship for the summer, by long distance I mean we only see each other once a month until september because that's when I'll be back to university & so will he. (We go to the same university) .. I'm 20, he's 22.
Basically, I have a friend who I guess I had a thing with. I mean we liked each other, we kissed and what not but it didn't go anywhere so we decided to be friends again. My boyfriend knows about him; I tell him everything. So the other day me and this friend along with a bunch of other friends met up & we had a good time, no weirdness. I got home and my boyfriend asked me how it was, so I said I had a good time. He said how was the friend, did he try anything with you? So I said no, he was normal. I told him i missed him and i wished that he was there and then I had a massive migraine & fell asleep. (I tried to stay up and talk to him but I knocked out) so the next day, he was acting slightly off with me. I put it down to him having a long day at work and didnt think anything of it. I like to give people space so I thought id let him talk when he wants to. So anyway, after a while he messages me with a long paragraph talking about how me not telling him what happened with the friend made him speculate alot of things, he drew his own conclusions and decided that I still had feelings for this friend. He said he didnt wanna stop me from ha ging out with him or whatever but that he was worried that in a few months I'd realise that I'm only with him out of spite, or I'm confused or I'll wanna be with the friend. He also said that I always have an 'I dont care' attitude when there's something up with him. He said abit more, emotional things etc etc.
So I replied the next morning and reassured him that nothing happened. I recalled the events with the friends detail for detail to ease his mind. I didnt comment on the other things he had said as I felt a little upset at the thought that he thought that I didn't care. We always tell each other we love each other and I've basically in not so many words said i want to spend the rest of my life with him. We're quite romantic and tend to make things for each other all the time. I like writing, so I send him my poems and pieces of writing to him all the time (about him of course) and he tells me he loves it, that he feels special because it's unique. So him saying them things just upset me a little, I felt like he was doubting my feelings, my trust. And it's not the first time this has happened.. he'll get insecure not necessarily about a guy but in general, and he'll blame me for acting like I don't care when I clearly do.

So I tried to be normal, casual convo, etc.. but it was nagging at the back of my mind.. so I mentioned it to him. I told him how he made me feel, and that I felt he didnt trust me bla bla. And he rreplied with his own insecurities. Told me he was scared I'd realise I can do better than him. That he isn't physically atrractive and id want someone else. Bla bla.. he said sorry about making it seem like he thought I didnt care but that it comes across like that sometimes. (I dont think it does) .. I didnt really 'feel' the apology or his explanation. I reassured him about the insecurities then said I was going to sleep.. he said that he does undermine my feelings alot coz he forgets that I'm in love with him too. But I'd gone to sleep.. I didn't want to argue, talk or discuss or whatever we were doing.
Now he's talking like normal, like nothing was said, and it wasn't an argument as such so basically my problem is that.. why do I feel so distant now? (Besides the actual distance ) ... he'll talk and I don't want to know. I cant help it, I'm not replying properly either. He hasn't noticed, or if he has he hasn't said anything.. I don't know if its coz of the stuff he said.. it made me feel like he thought I was shallow etc. But I think I could get over that seeing as he apologised. I thought I did get over it but something has changed.. I don't feel like he's idk.. amazing anymore. I guess it's not that, I think im confused. Idk how I feel right now, but I know I feel sadness & distant. I don't want to talk to him but I know I want to be with him. Why do I feel this way?