Late 08, early 09 when I was with my gf at the time (we broke up since, unrelated) that's how I was regarding school and such. Because I didn't know what I wanted to do (like my major) I got fed up with applying for scholarships because they all wanted to know my major (which again, I didn't have). I was taking classes in college, but I had no direction in which ones I was taking (just vaguely by what was listed in the Assoc. of Arts req.). Which sucked. All I wanted to do was to crawl in a hole and die or something. Anywho. I can attest to the frustration/glaze he feels to your encouraging because (as hard as you try) he's hearing it from 100 other angles too (not to diminish your importance in his life). But now, I've talked to the right people, and I know exactly my plan for school! It gives me so much drive now to have at least a general plan. It just took time.
So, all that to say: 1) Continue to love, support, and encourage him but you might try just sharing in his feelings instead of always offering advice/encouragement. 2) Don't let him give up. If he is looking, something will turn up in time. And has he tried starting his own band? But yeah, don't let him give up. On God or on the band. 3) I personally don't believe that God gives you passions and talents only to ignore/crush them later. 4) Granted, I don't know your exact situation, but I wouldn't necessarily assume that he is giving up on God. Encourage him though to keep close/grounded with God because even if the band thing doesn't pan out (I hope it does though), he still has God for one, and then you and family. 5) When I was down in the dumps, sometimes I just needed a hug, a little time, and then some fun. Focus not on his lack of being in a band, but more on your next date or something.

6) If he doesn't end up in a band (successful or not) by his own will (as in if he chooses to follow something else) don't take that as giving up. As long as he is with God and content with what he's doing, that's still good.
Oh dear. I'm sorry I'm so long winded. I hope I helped. I'm not Dr. Laura or Dr. Phil or anything, but I hope it helps. Good luck.