When he's stressed, he becomes aloof. This stresses me. What to do?

I understand his personality – and I’m fine with it most times. But it really stresses me out, even though I understand. I hurt when he’s hurting – I really want him to talk to me about what’s on his mind.

Sigh.

What should I do, males? I’m sure many of you are the same – help me understand what might be going through his mind! [The stresses he is experiencing are external to the relationship, they aren’t because of me.]

I like to talk about what bothers me. He doesn’t.