How often do you get to talk on the phone?
My fiancé is a Marine, but he is stationed at Camp LeJeune ... hasn't gone overseas yet. We get to talk on the phone nearly every day when he isn't in the field, and I know I'm so lucky for that, but it is still hard on me to be so far away from him.
I'm in a Marine girlfriends group on Facebook and it's very supportive. I suggest you meet other Marine girlfriends/wives/fiancées because there's nothing like having somebody REALLY understand what you're going through.
Also, something one of those women suggested was that you seperate "think about him" time from everything else time.
Good luck!