Hi Lynn,
There are quite a few reasons this might be happening. Online sites are great for getting information to help ask all the right questions but can not take the place of a doctor's solid medical advice. If your boyfriend thinks he might have something serious going on, he should seek the advice of a doctor.
Here is some information that might give you some ideas on how to approach this. You can read about erectile dysfunction here, the basics and what some of the causes are. The symptoms are listed here. There is a good section about coping here that might have some information you find helpful. The Harvard Health Publications group posted an article here about men who have orgasms without erections. You can read the full article here.
I hope this helps. I know it can be troubling for a partner, but if you think this is something that might be more serious, it might be time for your boyfriend to see a doctor.
Take care and stay in touch. Let us know how you are doing!Vicki M