Listen to him. That's really all you can do. Encourage him to communicate with you as much as he can. It seems like he may not be communicating his issues as clearly or as well for you to understand. That's not his fault either...obviously he's suffering and like a lot of people who suffer from anxiety, communicating it to others is so hard. It's hard to open up about it. But of course, his anxiety is in turn causing you anxiety, which is not good. You need to tell him that, as well. It's not your job to save him, but you're together for a reason and you're not breaking up for a reason. My best advice is to really get to the nitty gritty about everything, even the stuff that hurts to talk about. Maybe go to a therapy session with him as well. Good luck.