Nymphomania fell out of favor with doctors in the Politically Correct 80’s. Swearing that there was no such thing.
There was always a debate whether it was a mental or physical condition. I’ve read about Vivian Leigh. Jokes aside. She lead a sad life picking up some really rough guys night after night. She really couldn’t satisfy that itch.
There’s a new term out now. Persistent genital arousal disorder (PGAD) . Sure sounds like the same thing to me. Only now it seems to be seen as a physical condition.
Odd how the term nymphomania isn’t mentioned (except in the Wiki article). But isn’t PGAD just a politically correct term for the same thing?
I am pretty sure that the condition where women experience continual orgasms does not bear much relation to the popular notion of nymphomania. As I understand it, women with this condition quickly come to strongly dislike having so many orgasms, and do what they can to avoid it. It does not lead them to seek out sex. The other case you describe may be a different matter.
The fact that she would have rubbed her genitals raw by that time. Plus, as stated, multiple orgasms over long periods don’t feel nearly as good as you’d think.
And, to answer the OP, the concept exists in the same way you can be addicted to anything else pleasurable. It’s defined as when your want for sex overrides your actual needs, like food and shelter. It’s when your inability to control your desire for sex causes problems. It fits the general definition of a mental disorder.
People have claimed it doesn’t exist, as it was previously used to mean people with a high sex drive who had no problems dealing with society.
The condition described in the OP sounds more like the equivalent of satyriasis than of nymphomania. Satyriasis is the male condition of having a hard-on which won’t come down (in some cases caused by misuse of drugs - legal or illegal), or getting aroused too easily.
The physical condition described really doesn’t sound like nymphomania. However, it is probably what is referred to as sexual addiction now. The problem with nymphomania is that it was sexist. It comes from a time when women were not supposed to be that sexually aware. The same condition was winked at in males. Sexual addiction can occur with males or females.