Stress = Rare sex?

OK, let me state first that I LOVE my BF, he means so much to me and likewise me to him. We have been living together since last October. When our relationship started the sex was amazing we were having it so often, I thought I would have to schedule "off" nights, lol. Well he is a Marine and he was injured in Iraq and has been dealing with his injuries since 2004. For a while, he thought the Marines were going to discharge him for his injuries, but didn't know when. Well now he is "fit for full duty" and doesn't get out until this November. This has brought him a lot of stress trying to translate into the civilian world and now he isn't going to get near the amount of money he would have if he had been discharged. Pretty much ever since he found out sex is a rarity only happening a few times a month. He is always thinking about how he is going to afford stuff and what job can he get and where he is going to live that all he wants to do is veg out when he gets off work. Sometimes I can catch him on a good night... but I leave for my next duty station in 2 months and won't see him after than for another 8 months! How can I up his sex drive without putting aside his worries. I want to be his focus again... his lack of interest makes me feel a little un-wanted sometimes. And no, he isn't having an affair, we spend all of our non-work time together...

Any advice?