Rosetta, single again at 47, felt compelled to apologise publicly to Anneka."Tom used to tell me that Anneka was neurotic," she explains, "and that she tried to come between him and his children from his previous marriage."I got to the stage of wondering why he didn't leave Anneka sooner if she was so terrible. Now I know he's saying the same sort of thing about me."Some mistresses are satisfied with playing second fiddle to the wife - or realistic enough to know that the relationship wouldn't work any other way - but most, like Rosetta, live in hope that one day the situation will change and the man will be all theirs.
As Sir James Goldsmith famously put it when he divorced Ginette Lery and married Lady Annabel Goldsmith, "When you marry your mistress, you create a vacancy." And he was something of an expert in the field, at one stage maintaining three relationships (and families) around the globe. "I felt like I had to sleep with an emotional gun under my pillow – I needed to protect myself at all times," says Nicky, 35, who married her lover after they had both divorced their spouses.
People deceive themselves that they will continue to be this more attractive self if they end up with the lover full time, which just isn't realistic."An affair is just a part of somebody's life," explains Dr Reibstein.
"It's a response to something that is deficient in the marriage." If a marriage has become stale, if the passion has gone, an affair can fill that gap.
"They think that by sharing the deep stuff they are showing their real selves, but actually the trivial domestic stuff - such as whether you leave the toilet seat up - probably says more about you."Marian's lover David was not being deliberately dishonest by hiding his bad habits for a decade.
Part of the allure of an affair, says Dr Reibstein, is that it allows you to believe that you are that more interesting person you show to your lover on your precious, snatched weekends.