A male friend once confided in me that his silly bit of fluff was getting pushy, writes Carol Sarler - who thought the woman was a "bunny boiler" - a reference to the movie Fatal Attraction, starring Michael Douglas and Glenn Close, in which a married man has a weekend affair with a woman who refuses to allow it to end, resulting in emotional blackmail, stalking, and an ensuing obsession on her part.

London - Once, during a chilly country walk, my lover fondly twined his scarf around my neck to keep me warm, taking it back only when we parted, hours later. As he wrapped it around his neck, it was left to me to warn him not to wear it home - he was married and his wife was bound to smell my Chanel on it.

For, while I felt no guilt at having an affair, I fully understood the rules of getting involved with someone else’s husband. There is, if you like, an etiquette of the illicit which is vital to protect the innocent in these situations - his partner, his children. I speak, candidly, from experience.

In my lifetime, I have had three lovers who were married. I don’t, I’m afraid, feel lingering guilt about it, partly because in my friskiest years of the Seventies and Eighties, with the Swinging Sixties still in our memories, everyone was more licentious than they are today. And even the nicest girls weren’t terribly restrained.

Partly though, it’s because even if I know what I did was wrong (OK, very wrong), I also know nobody got hurt - except, obviously, me - because I did know the rules of having an affair.

First, you have no rights. Your feelings and your needs are at the bottom of the heap: below his wife’s, his children’s and their hamster’s. So no, you may not phone his home - ‘just to hear his voice’ - and slam it down if his wife answers.

Neither can you ask to hear from him during weekends, holidays or at Christmas, regardless of your loneliness or sudden illnesses. You are on your own. You will not send saucy emails or photographs that his wife could stumble upon on their home computer - even if he asks you to.

You will meet him only at your home or a hotel; if you do venture a meal out, it will be at some far-flung diner where anonymity is more important than the length of the wine list. In short, you will master discretion at all costs (as did, famously, the then Camilla Parker Bowles).

Sometimes, you have to be more vigilant than the man himself - men tending to pay less attention to detail. A friend had a lover who would spend the occasional weekend with her, having told his wife he was on a business trip overseas. It was her idea, not his, that she kept a supply of duty-free carrier bags at home, with a bottle of Scotch in each, to authenticate his story when he arrived home carrying one.

At the heart of all this discretion, as you must keep telling yourself, is that it does not matter how much a man claims to dislike or resent his wife, that woman has done nothing to you and you have no beef with her. He is hers, not yours.

Clever men should be able to spot from a mile the women who just don’t get this. But far too many don’t. A male friend once confided in me that his silly bit of fluff was getting ‘jolly pushy’, as he called it. He had noticed that, ever so slowly, she was arranging rendezvous at restaurants nearer and nearer to his home. ‘Get rid!’ I yelled. ‘She’s a bunny boiler!’ In the end, he didn’t, they were discovered and his family was destroyed.

Many mistresses exact revenge not upon the miscreant himself, but upon his family. Leonard ‘Rigsby’ Rossiter went to endless trouble to keep secret his affair with broadcaster Sue MacGregor. She waited until he died, then published the story - causing unimaginable pain to his wife and children, who had no idea about the affair.

In similar vein, a widowed friend of mine visits her husband’s grave every year on his birthday, only to find herself beaten to it: a dozen red roses are already neatly in place.

We don’t know who puts them there, but I’ll wager it is an ex-lover. A woman who must know what this does to my friend to see them there.

As for me and my married lovers, they became little more than lessons harshly learned. With the clarity of hindsight - and with passions calmed by time - I now think only the last of them really might have been a lifelong mate.

I loved him, he loved me and our compatibility extended way beyond the bedroom. Then, one day, after months of telling me he was only waiting for ‘the right moment’ (huh!) to leave his wife Julie - oh, and that, naturally, ‘that side’ of their marriage had been over for years - he casually announced she wished to try for a baby.

We all have our cut-off moments and that was mine. I’m not claiming that I was suddenly overwhelmed with guilt at my actions; simply that I realised a) this meant he would not leave Julie, b) he was lying about ‘that side’ of things and c) I could not mess with the lives of babies. Even babies not yet conceived.

That day was our last together. The heartbreak lasted longer than the relationship did and I never trod that path again.

The rules of an affair, I discovered, are too hard and too punishing - even if punishment is exactly what I deserved. - Daily Mail