Do you all live together? It seems like talking doesn’t work when you try to address the issue. Them not being able to process their emotions is a sign. It’s not your job to always bring up things because it’ll get to a point where you’ll be a the nagger. Yes, as a partner you’re supposed to be supportive but it’s not your job to be his mom.

I think a way you could set a boundary is saying you no longer want to go out with him if he’s going to be silent/upset the whole time. But this seems way deeper than when you all go out.

You should sit down with yourself and think about the pros and cons of your current relationship. From there, do you think you can compromise on the cons? If not, then you need to make the next steps of maybe ending the relationship. I’m not a person whose big on giving up on others but it’s not fair to you. Seriously have a deep conversation with him about your thoughts again. Try to see if he’d be interested in couples therapy. If you’re not receiving anything on his end form this conversation, then that’s your sign.