I will tell him what I think when it is the right time, if I think something I can tell him is the best.
That could even be, however awkwardly, to tell him to admit that he has lost his footing and pull the plug in some way and go to a summer house on a distant coast to find the energy again.
But I don’t think it will come to that. Because for all my doubts I know him well enough to be able to think of better advice and action, like suggesting that we go both to that summer house to discuss the plot of a new role-playing game. Purely recreational, of course. Nothing to do with his actual need to go there.