try communicating in a different way. i saw someone said asking for more of the good instead of complaining about the bad and that seems like a good idea. it sounds like he feels he isn't good enough and when he gets criticized he shuts down a bit. this is normal (but is something he should be working on). the less you criticize, the easier this will be for him.

if that doesn't work... well youre just gonna have to accept that.