Without knowing what the condition your boyfriend has been diagnosed with actually *is*, I can't really tell you anything. I find it very hard to believe that he can't have surgery for it, whatever it is, before he turns 18. In most cases, if there is a genital/urinary problem that can be corrected by surgery, doctors are eager to get it corrected as soon as possible.
I do not personally know of any disorders which would make it considerably uncomfortable for a man not to ejaculate once he had become sexually aroused. Given that most normal men experience erections (with or without actual sexual stimulation) anywhere from 4 - 12 times in a 24 hour period, the vast majority of which do not end in ejaculation, it seems like he must be in pain almost continually.
If there is in fact an ailment that your boyfriend has been diagnosed with, and you can provide us with the name of it, I'll be more than happy to go do some research and let you know what I know about it.
On the other hand, maybe you'd better go read this article right here: http://www.scarleteen.com/pink/pages/fbi_blueballs.html
In any case, if your boyfriend is experiencing pain because he has not been able to ejaculate, a quick session of masturbation will cure that. It'd be very supportive of you to tell him that it's perfectly okay by you if he goes and masturbates. I'm sure you wouldn't want him to be in pain, and I know with 100% certainty that masturbating can take care of the problem of him not having an orgasm, and that masturbation will do it without putting either one of you at risk of an STD or pregnancy. It's the best solution.
Start a Revolution -- Stop Hating Your Body!
[This message has been edited by Hanne (edited 12-09-2000).]