Are long distance relationships good for young teens?

My girlfriend just went to a boarding school in Maine, 600 miles away. This has caused me alot of grief as we've been dating for 9 months now with no problems. I'm turning 15 years old this month and would like to know if long distance relationships like this are safe for a teen my age. She's one of my first girlfriends and means alot to me, but i don't know what to do. HELP!!!