Relationship question!

Hello ladies! I have a question for all of you, I've been causally seeing this amazing guy for about 10 months now. We both found out that he is going to be deployed for 6-12 months and he will be on missions where I cannot even know where he is and we aren't sure how much he will be able to contact me. The only thing that is keeping us from making it official is the fact that he is leaving. He feels as though he is abandoning me because he has to leave, although this is such an amazing opportunity. He says he can't do distance, mainly because he did it once and the girl hurt him very badly. So he is afraid of getting hurt, and afraid of being distracted by wondering how I am and if I'm okay when he is in the middle of a war zone. He feels like it isn't fair to me because he won't be here to be apart of my life for who knows how long. I've tried to talk to him about it and it makes him upset. I'm not sure if it's because he knows what is coming and I know he cares a lot. I'm not sure what to do. Any thoughts?