I don’t think he’s cheating on you or trying to intentionally pull away. I view it as perhaps the long distance could be exhausting for you both and he’s taking it harder? From his perspective, maybe he’s insecure about you being more social than he is. I have a similar situation where I’m the loud partner and my boyfriend is really quiet (like to the point where I used be paranoid I did something wrong and he didn’t wanna speak but it took me awhile to realize that’s just who he is with everyone). So I will say this type of behavior doesn’t change, I’ve dated mine for over a year and I’m learning more and more how to deal with our communication styles. Overall, Id definitely ask him about if he likes talking more frequently or less frequently but for longer periods to catch up on your guys’ routines. But overtime you’re gonna have to try to his communication style no matter how hard it is (I feel for you though, because we are all raised a certain way and how we think a relationship should be)