Mature Age Sex

I've always wondered when does a couple stop having sex... at around what age? do you just not want or enjoy sex one day? Do you go through menopause and then stop wanting sex? Is that around about the same age men stop wanting sex? it all kind seems a bit gross in my head (visualising) so I thought I'd just ask to find out the facts?

I GUESS WHAT I'M ACTUALLY TRYING TO ASK IS... What is the point of sex for a woman after menopause? Does she want to have sex after menopause?

If we have sex to reproduce and if those reproduction years are limited to x amount of years, which menopause marks quite clearly... no more babies now... period stops... do her baby making hormones also take away her desire to have sex?