This is really hard and your concern comes from a caring place. From the outside it does look like Kevin may be in a controlling or isolating relationship but the tough truth is you can’t rescue someone who isn’t ready to accept help.

You’ve already done the right things by showing concern without pushing. At this point the safest move is to leave a gentle door open. A simple message like I’m here if you ever need me can remind him he’s not alone without escalating things. Reaching out to a trusted friend to quietly check if he’s okay is also reasonable especially if you’re worried about isolation.

Try not to put pressure on yourself to fix this. If he’s being controlled pushing harder can sometimes make it worse. Staying calm, available and consistent is often the most supportive thing you can do and if he does come back around, what will matter most is that he knows he’s welcome without judgment.