Why do men shut down when stressed?

My boyfriend and I had a bit of heated talk yesterday and now he is acting pretty cold with me and quite distant. I’d like to talk it out but don’t want to push him and cause him more stress. I want to respect his feelings and what he needs but
the quiet is making me scared to lose him.
Is this how some men process things, by going quiet and taking some time and space? I care about him a lot and I’m really happy with how things are going between us so I’m worried he doesn’t want to be with me anymore
Why do men shut down when stressed?
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