One consideration would be to test the testosterone level (both free and total testosterone) - which decreases with age. It is possible that a low testosterone level may be affecting your orgasms.
The fact that you are able to maintain an erection suggests that the penile vasculature and nerves are intact and functioning.
For further evaluation I would be evaluated by a urologist. If everything checks out on the exam, testosterone levels, and imaging studies, you may want to consider counselling to address this issue.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Thanks,
Kevin, M.D.