ITS name may trip easily off the tongue, but illicitencounters.com couldn't be more specific in its lurid intention.

Touted as the UK's largest dating site for married people, with 760,000 members and counting, it has announced a 5000-strong surge in sign-ups during the first part of this month. And here's the rub: most of the new recruits are women. In Scotland, the majority are from Aberdeenshire. Infer from that what you will, but personally I find it depressing to think that a husband's absence on a North Sea oil rig is sufficient licence to seek a good drilling from a stranger.

The website trills: "Our members are all looking for a little romance outside their current relationship. Whether that's the occasional bit of flirtatious chat, a regular coffee date, or a full-blown affair, that's up to them."

One member actually claims her affair saved her marriage. Another says she and her long-term lover meet when they can "with no harm to anyone else".

They don't specify, but I bet their spouses aren't in on it. Infidelity, after all, is predicated on secrecy and dishonesty. So however innocent they try to make it out to be, a regular coffee date with a married man in this context constitutes emotional betrayal, at the very least.

The BeNaughty.co.uk dating website invites single men living in the UK "to meet the right single ladies" and encourages those who are "unhappily married or separated" to join. Plastered with young half-naked women in provocative poses, it seems to imply that sex with detached or semi-detached women is attractive, because their emotional energies are engaged elsewhere.

In Paris a series of posters has appeared, advertising the Canadian extramarital dating website Ashley Madison – which claims to have millions of members worldwide and publishes lists of cities where "wearing a wedding ring will get you laid". Featuring a beautiful young woman, it asks men if they know where their wives are and suggests they too should try an affair. It's been accused by a rival website of being a "business built on the back of ruined marriages and damaged families", but its founder insists a website will not convince anyone to commit adultery.

Who are these people trying to kid? Sites like these specifically target the young: one actually states it's not for the over-50s. Tapping into the liberally-inclined social networking culture, they strive to normalise the kind of behaviour that, for women especially, used to bring about disapproval, social exclusion and worse. By making adultery appear cool, they exploit the new libertarian moral climate – and make a fortune from trousering membership fees.

If the figures are true, increasing numbers of young people appear to have become so self-regarding and obsessed with instant gratification that the idea of being in a marriage for the long term is now anathema. It's the young women I worry about. We find it harder than men to keep sex emotion-free, yet they seem to believe, in the Shades Of Grey age, that life can carry on as normal while they play with emotional fire.

Playing around within a marriage or long-term relationship rarely ends well. Gordon Matheson, leader of Glasgow City Council, has publicly apologised to his civil partner for being caught with another man, and his remorse seems genuine.

An attempt to return to old-fashioned fidelity emerged in the BBC soap EastEnders this week when the adulterous and remorseful Kat cautioned another woman against pursuing a man who has been with the same woman for 17 years and has two daughters with her.

Her advice was to move on and let go, because "it's no fun, it just leads to misery and heartache".

The once-mighty influence of domestic television dramas may be diminished by the global reach of social media, but I believe the false allure of adultery could yet be killed stone dead if women just remembered that it's us, rather than men, who ultimately have the power to just say no. So girls, get a grip.