My first reaction is, "Who cares what the reason is?" I mean, that's sort of lesson #1, right -- whatever Walkaway's reasons, they're Walkaway's reasons. The reasons change, morph, evolve to suit the day, the hour, the instant. Walkaways. Shapeshifters.
Yet I can't deny that we all want to know Why. If there were a clear Why, then we'd be able to Fix The Problem.
So could it be that he's having some hydraulic difficulties? Certainly. He's the right age. The gods know I've learned that lesson recently -- my tennis serve doesn't have quite the "snap" it used to, if you catch my drift (and much to my chagrin).
But is that something you can bring up? Only you know the depth of the intimacy -- on a non-sexual level -- that you share.
Could it be depression? Certainly. Could it be both? Certainly. Could it be something else? Certainly.
And therein lies the basic risk, I think, of your bringing the matter up. It could be a near-infinity of things. Does bringing it up get you closer to your goal or farther away?
Now you could approach it, as @Thinker did, in a Star Trek-inspired vision of bold exploration. It has long been my personal belief that there is nothing quite as splendid as being in the midst of rinsing the soap out of my eyes in a steamed-up shower and suddenly noticing an extra pair of hands (female, thank you very much -- not that there's anything wrong that, LOL) weighing in to lend a, ahem, "hand." The boldness of it intrigues me rather a lot, as does the obvious direction such assistance -- purely humanitarian, mind you -- could go.
Boldly go where no one....
However, that's the kind of thing that could backfire. Could result in all sorts of awkwardness.
This, I think, is something only you can sort out. So is it possible that Himself's pump needs some priming? Certainly. But is that the $10,000-Question in your sitch? Again -- only you can answer that.
