Totally possible. Whether I could maintain a relationship in law school was something that I was worried about as well.
My girlfriend goes to grad school about an hour a way and I spend every weekend with her. Studying in her presence, as was brought up in another posting, works out real well. I take Friday off once classes end, go out with her Friday night, study in her presence Saturday, go out Saturday night, and study again in her presence Sunday, until I go home on Sunday night, to study even more. During the week, she goes to school and studies, as do I. The weekends, we have a good time while also getting things done.