That's weird. It's sort of like what happens to me on certain antidepressants. I get excited easily enough, but then I can't seem to, you know, GET anywhere, and then I lose interest...

But it doesn't sound like he is on meds.

Do you know if he can masturbate OK?

It's complicated...there are so many things, mental and physical, that can impact performance.

I think if you talk about it out of concern for his health, he may take that as a caring gesture, not a criticism. If I were in his situation, I'd see a doctor...the situation doesn't sound like much fun!!