You have to fold or go all in like people said. Long distance will NOT work. She will be far too busy for trips home or to entertain you if you visit. She will be an emotional wreck with the stress of school and being away and will easily find comfort in one of the hundreds of other doctor to be guys who are probably taller, stronger, smarter, richer, and better looking than you.... but most importantly: available. I've seen it happen over and over and over in my grad school.