I've never witnessed it!

@Alethea "there can also be psychological causes like stress or depression that affect libido, not to mention underlying medical conditions or medications" This is true, they're supposed to look for medical causes first.

I've known a few men like this, I think it's more common than people think in both sexes. Not everyone is gagging for sex the whole time

I know one man slightly, a highly erudite and witty man who's a kind of throwback to the 18th, who has no interest in sex whatsoever. He's married! - very happily too. They have several cats. I think there are more 'marriages blancs' than we imagine

My friend has a happy marriage like this -- they just don't care that much about sex. Two Scorpios btw, both attractive and kind. They go like six months without and then have sex like maniacs for a week and then back to nothing.

I'm surprised she told me but I'm glad she did because I think the more people talk normally about this stuff the more accepting everyone becomes.

Ive read in quite a few places that damage to the nervous system is one factor that can cause this. There are many things that can damage it, and one of them is being oversexed. Too much sex or masturbation, causing a lot of semen to be discharged dissipates the vitality of the mind and body. Its kind of like 'burning all your candles of happiness at once'. When so much of society is obssessed with sex, it can lead to unnatural imbalance in sex drive. Some guys have the vitality to keep burning for a lifetime, but many dont.

Dre, sorry but I don't believe that's true.

I'm 66 now, and from all that I've seen, men who are really keen on sex stay keen until they are well into old age, if not until death. I've known men like that still having vigorous sex lives into their 80s (like the artist Lucian Freud), and it doesn't debilitate them at all - quite the reverse.

Men who aren't much interested in sex remain that way - many try it a few times when young or even marry, but live a mostly celibate life.

We don't hear about it because men don't like to talk about it. It's why prostate cancer is so hard to talk about. Who wants to talk about cancer that can cause your penis to stop working?