When Alice (not her real name) sent a flirtatious Facebook message to an old flame, as her husband slept beside her and her children soundly in their beds, she didn't feel a shred of guilt. "We hadn't spoken for eight years, but I knew he still held a torch for me," she says. "I worded the message carefully. I wanted a result and I knew how to get it. It's surprising how anger can make you very focused."
Just days earlier, Alice, 42, had discovered intimate text messages from another woman on her husband's phone, suggesting he was having, or was about to embark on, an affair. "They were purely sexual, it didn't sound like it was a love affair, but I was devastated," she says. Yet instead of confronting him, she festered - sorrow turning to simmering anger and, ultimately, thoughts of revenge: "My overriding feeling was one of rage, that I had got a raw deal - and I wanted to right it. There were plenty of men I could have flirted with over the years, but I always remained true to my vows. When I discovered he wasn't playing by the same rules, it seemed licence to not make all those sacrifices any more."
The psychology of the "tit for tat" revenge affair seems to elicit - if not sympathy - then at least more understanding than most infidelities. Who, however faithful themselves, can't have thought "fair enough" upon reading Jerry Hall's confession, yesterday, that her well-publicised fling with wealthy horse breeder Robert Sangster in the Eighties was purely designed to give Mick Jagger a taste of his own medicine after yet another dalliance?
Instead of the moralising rebuke that often follows a public admission of adultery, Hall appears to be deemed a mascot for wronged (or at least disgruntled) women. Much like Diana, Princess of Wales, who is thought to have embarked on her affair with Dodi Fayed to make her former lover, Hasnat Khan, whom she wanted to marry, jealous. Or Sienna Miller, who embarked on a two-week fling with Daniel Craig mere months after her partner Jude Law (and Craig's best friend) confessed that he'd slept with his children's nanny.