I am in almost the exact same situation as the OP. I did long distance with my SO while I was in undergrad. I moved in with him for this gap year during applications and now I'm moving 3 hours away to get my PhD. It is certainly doable to try long distance again but I had to make a decision based on what I thought would make me happiest (and him in the long run). I will not do long distance again. It was really, really hard on us the first time around and I don't want to go through that stress when I'm trying to focus on my career and schooling. He has a great job in our hometown and he doesn't want to leave it. I get that and I don't fault him for it but I also won't waste the next 5-6 years of my life trying to make a long distance relationship work when in the long run, he will probably never want to move and I will almost certainly have to live somewhere other than my hometown. It's pretty awkward living with someone when you both know the exact date your relationship will expire (September 1st for us) but we don't hate each other by any means. It'll suck at first and it'll take a few months for us to be able to talk again I'm sure, but I think we will stay in touch enough to remain close. We have agreed that if at some point in the future something changes for either of us (I could fail out of school after all, or he might decide he hates his job) then we will revisit the issue. I think the plan is to revisit how we're feeling about each other next summer. If we have moved on in a year then maybe it wasn't meant to be. If we haven't then it might be worth trying to make something work.
It sucks the OP's SO isn't comfortable discussing things because I have found that communication was the only way we were able to get through this sticky situation and come up with a plan. Since it seems like the OP is being left to make a decision, I'd advise to try and figure out what it is that YOU want. Are you certain your SO is "the one" or do you have any thoughts that maybe there is still a relationship out there you'd be happier in? If you're not certain, then maybe the time apart will help you figure it out. Maybe you don't need a formal break up but you guys could agree to just take some time apart. If he still refuses to even discuss THAT then, if it were me, I'd take that as a signal that I'm going to have to make the decision and just run with it.