It's difficult for me to answer this question because I haven't heard from your boyfriend. Without knowing his feelings, I can only speculate as to what's going on.
Certainly, the wrong size or style of condom can inhibit sensitivity--especially if the condom is too big (not too small). The best way for your boyfriend to determine whether this is true for him is to experiment with different sizes and thicknesses while being sexual with himself. Once he finds the style that gives him maximum sensitivity, you can try it together.
Some men psych themselves out--in other words, once their erection goes away EVEN ONE TIME, they begin to worry, thus creating a self-fulfilling prophesy. The way to change this is to remove the stress and worry and focus on pleasure. Don't make penis-vagina sex (p-v) the main event, with all the anxiety attached to it. Rather, put the condom on during pleasurable touching, playing, etc., and let things flow from one activity to the other.
It's also important that he use a bit of lubrication in the condom tip. This will make it slippery and enhance sensation. Of course, if he finds that condoms just don't work for him, then the two of you should investigate alternate forms of risk reduction/birth control. Best of luck to you. Dr. J
He says that he can't feel anything. He's pretty big, so we're using Magnum condoms, which he says fit better. Could they still be too small? ,
I have had the same problem for a while with my girlfriend and we found that when we didn't use a condom the problem went away which leads me to beleive that it was an issue with sensitivity. After experimenting with different condoms trying a very thin condom helped tremendously and no condom for foreplay was found to yield the best results.
This whole conversation astonishes me! It's because condoms suck! Build a relationship with him in which you can trust each other enough to have sex without a condom. If there's some medical reason why you need a condom, I'm sorry I opened my mouth.