well, i'm not in med school yet.... but i've been away from my SO for over 8 months!!!! he's in boston and i'm in los angeles: 3000 miles away. it's tough.... but we manage to talk to each other EVERY NIGHT... we're a technologically savvy couple, so we email, instant message [AIM], use an internet audio phone [Firetalk], and do videoconferencing [Netmeeting] all the time. all it costs is a hundred bucks for the webcam and twenty bucks for a microphone headset, but it's worth it! plus, we save on long distance charges!! we've been able to get together every couple of months for holidays and what-not. i think the most important thing to consider is how strong your relationship with your SO is... you need a strong foundation in order for both partners to commit to "making the relationship" work despite the distance barrier and stresses and time vacuum of medical school. best of luck!
