We're not married but have been together for over 8 years. I am away alone at med school. He is back home with my cat. We facetime three nights per week, write letters and record messages to each other. And try to see each other as often as we can. Third year will be hard I bet, since I think it will be more difficult to maintain this set up. But we shall see.
It is definitely hard on each of us. I miss him terribly and often feel guilty for leaving. He has always been amazing and supportive of my decision. But, I know it's hard on him too. My hope is to be back there for residency. So, no matter what I choose, location will be my number 1 ranking factor.
Edit: Just wanted to add that I am on the west coast. He is close to the east coast. So, getting back/forth isn't always easy. But, I'll be back there in only a few days!