For him it’s about being practical. If needs are met, there’s no reason to complain. But when needs are not met, then stress comes to the door. Mostly, men’s needs are around goals setting and meeting targets. For men, conversations of the heart don’t have a purpose in general but if they help meet an unfulfilled need they can be useful.
Find a quite time (perhaps before bed); to engage your partner in a conversation. Ask him “I see that you don’t look so happy recently, what’s up?” Offer self reflection questions like “what would you need to believe about yourself to feel this way?” He may or may not respond at the moment but the question will trigger a process of self reflection within him.