That sounds difficult for you both to deal with. I wonder about something that some people have that involves their nervous system. They have mis signalling sent from touch. What would feel good, feel like a tickle or maybe not be felt much at all to some people can feel like pain if the nervous system is not functioning properly. Does he have another things that you'd say this is happening with? Like an over reaction to textures of food? Or funky reactions to anything else? He's been checked out by a urologist which is good but wondering if a neurologist would help him. We process nerve responses with our sensory system and this can be dysfunctional.
And I'm sure it has been brought up the psychological component. Especially if it is uncomfortable, then that association is made and the reaction is had.
A sex therapist?
I think GuitarRox may be onto smthg w/ the suggestion that this could be related to some type of nerve misfiring. Maybe a Dr. could do some tests to determine if there’s normal nerve function.
Another thing to consider - since you say he’s never had the urge to masturbate, that seems extremely unusual for a guy of 22. That makes me wonder if he went thru a normal puberty - normally, guys going thru puberty have very high levels of testosterone, frequent erections (even without stimulation, such as sitting in class), and pretty much an overwhelming desire to ‘satisfy the sexual itch’, so to speak, so it seems really unusual NOT to want to masturbate. In that regard, has he ever had his testosterone level checked? Very low testosterone could easily result in lack of sexual desire, sexual dysfunction & possibly also lack of pleasure from what would normally be very pleasant sexual stimulation. I’d suggest he see his Dr. about this & get his ’T’ levels checked.
So - please try to get both nerve function & testosterone checked. Good luck to both of you & thx for being willing to work with him to fix this - some girls would just leave over such an issue. Please check back in here & let us know what’s found - we can all learn from this...