This is tough goodnessgracious! It's great that you show concern for your partner's stress level and seek more communication to try to help - it shows you care about the relationship. Now what to do if he doesn't show to be interested in talking to you about what stresses him out at work...

His decision to open up to you may at least partially depend on whether he sees the problem(s) causing him stress as temporary or permanent. Based on how much you know of his work, do you have an idea of what could be stressing him out and whether it's temporary or permanent?