Health Protection Agency figures show a 60per cent increase in cases of chlamydia in 2008 in this age group, compared to 2004.
And these soaring figures are set to surge still further in the decade ahead, as women, in particular, feel less inclined to put up with flagging relationships. In my own social circle, I've witnessed at least a dozen marriage breakdowns in the past two years - including the demise of my own relationship after 25 years.
In two instances among my acquaintances, the men, both in their early 60s, have departed to a much younger woman beckoning from a warm bed.
For me, in my 50s, the idea of taking my clothes off in front of a man who wasn't my husband was absolutely terrifying.
Having sex with a relative stranger, so easy when I was in my 20s, felt barely possible.
And if the menopause proves tricky to navigate, there's always HRT to help us through.
The Noughties was the decade in which women, for the first time, could say I'm Fifty And Fabulous or Sixty And Sensational and it was a genuine feeling, rather than just empty words.
And then, three months on, she did something completely unexpected and out of character: she started sleeping with other men.
Like many newly divorced women I've spoken to, it wasn't that she'd developed a voracious appetite for dating, but that in doing so she found an effective distraction from the pain of divorce.
In fact, she's 51 and the educated, successful director of a blue-chip company - with a 21-year-old daughter.