I am like that too. When I go over my limits, my tendency is to isolate myself.

I am better now, but I've been with a psychotherapist since 2020 and I am a lot better now at identifying my emotions and not isolate myself.

For me what worked was learning to identify my emotions. My first reaction to pretty much any negative emotion is anger and I don't think that will change. However, I've learned to identify the emotion after the anger and then I speak it out. Sometimes, just a small statement to myself (" I acknowledge this emotion X") and sometimes, it leads to a long thinking about the situation that caused the emotion and how that made me feel.

So to help your other half, helping him identify the emotion after the anger would be the first step.