erection without orgasm

i am 58 years old and have incredible erections but lately i am unable to have an orgasm although i have very heightened pleasurable experiences up to the point when i feel as though i am going to ejaculate and then nothing happens and the intensity of the pleasurable physicality of the sex goes away, but i still maintain a very rigid erection which is wonderful for my wife but i often fake an orgasm so as so not alarm her of my dilemma.  what kind of doctor can i see and or what can i do to achieve an orgasm?
Please offer some suggestions and i would be extremely grateful .
thanks so much

[tlh777]

you need to see a urologist and an endocrinologist.to make sure your penis and testosterone levels are fine.

[SeriousSam]

Very often this can be psychological, or even honestly boredom.  If you know exactly what each session is going to be like before you do it you might want to see if your wife has a problem with you guys mixing it up a bit.