I am 62, just divorced and have not been able to have an orgasm for quite some time. I can almost "get there" but can't quite push over the edge.
First of all, congratulations on being virile and potent at age 62!
If this is a sudden deal, like right after the Judge inked your emancipation papers, it's most likely upstairs in the cranium. If it precedes the separation agreement by a good bit, say a couple years, it may be something else, which a doctor can possibly analyze and treat. But if you're still getting hard with no issues, chances are good it's mental.
I was once - at a much younger age - in a similar predicament. Recently divorced and admittedly down in the dumps (depressed), I felt 'guilty' to have an orgasm without the now-former Mrs (a polite term, at best) at the center of it. That didn't last long once I realized I was 100% free, and I resumed my pre-marital twice daily jack-off habit in short order. Then of course, I realized I had carte blanche to start fucking other women, which I soon did.
Two simple suggestions to put your quandary to the test:
1. Go to a skilled masseuse who offers a thorough, certified massage with a very happy ending (believe me, she'll know exactly what to do) and:
2. Get a 'Fleshlight.' (Google it, even Amazon sells them) I had my doubts about these things but this is literally the best near-pussy you'll ever experience. In fact, it's better than half the women I've actually had. I tried one for the first time and couldn't last two minutes, that's how good they are. Lord only knows how much better the sexbots with similar syn-vag technology will be in the coming (!) years...
Bone-us suggestion: start fucking other women. If you can get rock hard at 62, and are having trouble cumming (gosh, you might just last an hour already...) you should realize at some level the value of yourself as a commodity in the over-40 dating market with these harpies. Never underestimate the receptiveness of a cat lady to long-denied hard dick.
If you still can't cum after getting hard and trying the above options, it's definitely Doctor time, and not in the kinky Zity sense...
Good luck.