When couples split up, loyalties are often divided. Nick Madrid on the dilemma of being the middle man
annie is sobbing down the phone saying David is having an affair. I say I'm really sorry to hear that and wonder if I should tell her that David told me a month ago. But he made me promise I wouldn't. At such morally confusing times I have one rule of thumb: if in doubt, lie.

So I lie by omission and say nothing as she vomits out her love/hatred of David. When she's finally run out of damning things to say - and I've long exhausted my limited repertoire of grunts and supportive but non- side-taking words - she says promise you won't tell David I've spoken to you. I promise, knowing that I'm about to lose two friends.

There is, in my gloomy experience, a dull predictability to what follows. David phones next day and asks me if I've spoken to Annie. I lie because of the promise I made to her and he tells me that Annie has found out about his affair. I grunt and murmur n-s-t words.

That evening Annie and David have a row. She tells him she's spoken to me and that I agree with her about what a shit he is - rather a liberal interpretation of a series of grunts and a few banalities - and he tells her that I've known about his affair for months. They unite to condemn the deceit and hypocrisy of their soon to be ex-friend. I wish I knew how to handle friendships with couples. Over the years I've tried not getting close to either partner but that just leads to superficial evenings of games and chit-chat. I've tried just being friends with one but if it's the man it's too stereotypical to be comfortable, and if it's the woman the man gets suspicious - often the woman too.

But as soon as I get close to both of them the friendship is as good as over. Both will confide in me, as you do with friends. And those confidences, at some stage, will be about the other partner. Is there a way to stop this? Should I say I don't want to hear? But then what kind of friendship is it if we have to set limits?

One way or the other - pillow talk or vicious rows - couples tell each other everything. When a couple are splitting they take no hostages. They ruthlessly try to get you to take sides. At such emotionally heightened times sex gets involved. However good a friend I've been, a male friend will suspect I'm having sex with his partner. And often that has been a possibility - not because I'm irresistible but because these are vulnerable times and sharing confidences can lead to other intimacies. But I try to be a good friend to both - to do otherwise seems to me like taking advantage. So although a score of times the invitation has been there, a score of times I've said no. Well, 19 times - nobody's perfect.

Friendship with a couple often comes out of an original friendship with one or other of them. It's not very often these friendships do go deep because it's quite rare to get on with a friend's partner. I'm constantly amazed at the awful people my friends have landed themselves with for long relationships. But when such relationships go wrong I'm especially on my guard.

I learned my lesson early, when my friend Vivian asked me to agree with her own analysis of the shortcomings of the partner who was in the middle of dumping her. "Well, I never thought he was right for you in the first place," I said, before listing his many faults. She agreed, oh how she agreed. Then she got back with him and neither one has spoken to me since. I've always thought the problem lay in the fact that singles and couples don't really mix very well. I know a woman who ditched all her women friends when she married because she didn't trust any of them with her new man. "I've never met a woman - including myself - who won't do a friend down for a man, however much she might agonise over it," she said. A depressing prospect - but not as depressing as the fact that most men wouldn't even agonise. When I became a couple myself I thought things would improve. Instead I find I've lost control of friendships with other couples. Now I'm unwillingly dragged into psychodramas via Angela, my partner. Elspeth, psychodramatist extraordinaire, phones Angela to describe the violent row she's been having with Tony most of the day. My partner says Elspeth should leave him.

Elspeth and Tony's row ends, as usual, in hot passion. He phones me to say Angela should keep her nose out of things and how dare she tell Elspeth to leave him. I get into a row with him defending Angela then tell her she was unwise to speak frankly to Elspeth. A heated argument follows. We're interrupted by a call from Angela's single friend Marjorie. Angela goes off to talk to her privately on the extension, presumably about my shortcomings. That's okay, I can have my say to Marjorie later. She's a friend to us both really.