First off, CAN he reach orgasm at all (even without a condom)? Has he been able to orgasm while condomless with previous sex partners? Does he orgasm while masturbating? If the answer is "no", then the problem isn't the condom. If THAT is the case, your boyfriend needs to look into other things that could be getting in his way. Being overweight or out of shape are known to inhibit sex drive, as can stress, many prescription medications (ESPECIALLY antidepressants), and other glandular or medical problems. It may be worth it for him to see his doctor about this problem and get a complete physical.
While I am like all other men in absolutely HATING condoms (and yes - the do reduce sensitivity), I still must say you should absolutely refuse to have condomless sex until you feel absolutely certain that sex with him but no condom IS safe. If there is even the smidgeon of doubt about whether or not he is being absolutely monogamous with you, and not engagging in any other risky behavior (illegal drug use, exposure to other people's blood or bodily fluids, etc.) Even if you ARE certain he's being loyal and safe, you still need to wait a given amount of time and have him pass a health screening before it's completely safe to ditch the condoms. The reason for this is that a person can have HIV for as long as 6 months (double check this figure) before he'll test positive.
While there are things other than intercourse you could do to get him off (oral sex, hand job, etc.), all of them do risk some exposure to you if he's not wearing a condom to prevent your having contact with his semen.
ANSWER THIS QUESTION