Depressed Boyfriend

My boyfriend enlisted into the Marines about a year a go. He went to SOI and enjoyed it. But now he's in 29 Palms and Hates it so much. He tells me how horrible it is and how he hates his life.  I feel so bad because I try to make him feel better and he gets angry with me for trying get him
in a better mood. He's coming home in a few weeks and I know he's going to hate going back to California. I need some advice with him, I feel so terrible.