Well, basically I've been with my girlfriend for about many years. We met in high school and went to college together and both of us went to medical school, she a year ahead of me because I studied abroad. I chose to go to a "better" school that was a few hours drive away (I realize this makes me look uncommitted) and we have maintained a long-distance relationship so far. Well, she is a fourth year student now and I'm a third year, and she wanted me to go to her school ball the weekend before my medicine shelf and I refused. And now we've separated because I am only looking out for #1 in her opinion and only expects things to get worse. I was very surprised by this because I thought after all the time we have been together something like this would not matter but I was way off.
Problem #1: Choosing a better career path that causes temporary LDR is NOT a sign of lack of committment. My boy and I are currently halfway through our 2 year 1200 mile LDR. Sure, I could have taken a less prestigious residency, but that would have hurt us both in the long run due to resentment, etc. A few hours drive is nothing - hell, you could practically see each other every other weekend if you alternated driving, maybe more. That doesn't make you look uncommitted at all, don't worry.
Problem #2. She says you're only looking out for #1, but wtf is *she* doing? Is she was not doing the same thing herself, why does she not transfer to your school, or something?
If this is a recent development, she may just be very stressed and you guys need to talk it over. The problem is, for a healthy relationship you cannot constantly put the other person before your own life needs. If they love you, they will accept bumps, distance, business like that (we're not talking extreme here, like moving across the country for 6 years - that would be extremely hard to swallow, but you know - like having to study for your shelf for example. If she's truly committed, she needs to understand that this is an important part of your own life that you need to address).
Since you guys have been together a helluva long time, I would really talk to her about this. As in face to face - not phone. Try to find some time to see each other and work this out.