Haven't heard from him in almost a week

Hello all. Sorry for the length but I really need help. Thank you in advance for reading my story. I’d like to provide some background to help with my situation. I have been going out with my boyfriend for about 4 months. Not very long, I know, but he is my best friend. We have told each other we love each other (not in love – I do believe this takes time and experiences to develop) and I am always happy when I am with him. One thing about him is that he is in the Navy but we are both college students as well. So over the summer, I saw him for a week while he had leave (we are not from the same place so we could not see each other for long). The rest of the summer he has been busy with the Navy. Right now he is essentially sailing to Boston.
Our relationship hasn’t been perfect this summer and I believe much of it is due to the distance, but he does not fail to tell me he loves me, misses me, send me nice and intimate messages, etc. He has texted me almost every day as well.
On July 31st we were talking about how time was flying by and we were getting closer to seeing each other again when I made a joke about how my football team was going to beat his in the first game of the season. He got very defensive and said he was changing his mind about visiting me the first weekend available and he was instead going to party with other friends somewhere else because of this joke. I apologized and told him that it was not to be taken seriously seeing as how I don’t even care about football and I did not realize he was that defensive about his team. He told me after I asked him to forgive the poor joke to talk to him when I was done being a baby, but I was confused by his statement so we continued to talk. The next morning I did something neither of us had done in a while (due to timing and comfort in the relationship I suppose) and I wished him a good morning, being clear that I had been up for a while so I was not being obsessive. Didn’t get a response. 12 hours later I asked when he was leaving as his trip to Boston was starting the next day and he didn’t respond to that either. I haven’t heard from him but he has posted some pictures on Instagram and he has had time to go into the city, so he has had time to at least say hello, but he hasn’t. I am also good friends with his sister. She texted him once and he did not respond. She said she was not surprised.
I am just really confused and hurt by his behavior. I know he is a lot busier than me so I have more time to think about it but these past few days have been terrible and I have been doing my best to distract myself. I have been on Instagram myself so I hope that has given him the idea that I don’t have to wait around for him. I’m looking for advice on what to do. There’s a lot more I could say but really I just want to talk to him and I miss him.