It is Friday afternoon, I think, but I've been staring at a screen all day and I couldn't tell you for sure. It is rare for me to achieve this level of concentration, and I am making the most of it. For some time I have been dimly aware of a tremendous amount of noise coming from downstairs, which I have thus far managed to keep at the periphery of my consciousness. I hear the door buzzer go, and then I hear my friend Pat laughing in the hall. He's been away, and I haven't seen him for months. I stand up and go downstairs.

In the kitchen my wife is serving supper to a large group of small boys, only some of whom belong to us. They appear to be engaged in a primary school re-enactment of a prison uprising. I say hello, take up a stool and slip into what I hope seems like a companionable silence; most of my brain is, for the moment, still upstairs. I'm having trouble following the conversation. The noise level in the kitchen is incredible. It's like being in a room full of parrots just as they sense an impending earthquake. Pat is laughing because he does not have any children and thinks domestic chaos is inherently amusing.

"How can you live like this?" he says. I look out the window and think, when did it get dark?

"Fortunately," says my wife, "I have the tireless aid of my helpmeet here." She is indicating me with her spread, upturned palms, and I realise that I am staring into space with my mouth hanging open. Pat laughs again, because he introduced us 18 years ago and still finds our marital union intrinsically preposterous.

The children get hold of a vat of ice-cream from the freezer and run off into the other room with it. My wife gathers the mostly full plates from the table and carries them over to the bin.

"And then I throw the food away," she says in a sarcastic, matronly singsong which the children and I have long come to regard as her normal voice. Pat laughs again.

"I couldn't live like this," he says.

"And then I would normally go to Sainsbury's to get more food," continues my wife, "but for once my husband is actually going to go instead. Aren't you, darling?"

"I guess so," I say. "Is there a list?" From the next room comes the sound of running, then jumping, then of a sofa rocking back on two legs.

"Did you ever imagine your life would be like this?" says Pat.

"You know," says my wife, "I went to my school reunion last week, and it was so depressing."

"Why?" says a child who is for some reason still sitting at the table.

"None of your business, flappy ears," says my wife. "Shoo!"

"Well," says Pat, "I simply do not know how you do it."

"Do you know what, Pat?" says my wife, suddenly turning round. "I've just about reached the point where I realise that I don't want to do it any more. In fact I don't think I can do it any more. I spent all last week seriously considering running away." It occurs to me that it might be wise for me to stand up and unload the dishwasher at this point, but Pat's sitting right in front of it. "I really mean it," she says. "I've had it and I'm going to run away."

Pat laughs, not so much, I think, because he finds this amusing, but because he laughs when he is nervous. I laugh as well, but not nervously. I know she isn't serious, because I know that when she finally goes there won't be any warning.