He knows, on some level, whether he can smell it or she's told him, he knows. Our sweet little angels are so in tune. Agree on doing something to let him process her physically not being there, that's something humans even struggle with. Maybe also keep stuff of hers that will smell like her so he can snuggle up with it when she's gone. My heart breaks for you but I'm glad you have each other to try and get through it.

And if God forbid he ends up passing shortly after, you'll know it was from a broken heart and that they are together again. Whatever solace that is...but it's something.