Time to say 'I do'?

At first glance it is hard to tell. We've got a lawn mower and a mortgage and a matching set of Ikea duvet and pillowcases. There is a pile of bills (big to small) on the hall shelf and a pile of wellies (big to small) under it. There are two carseats in the back of the car, along with the usual muddle of discarded socks and old sweet wrappers. There are papers in the door and curtains on a track in the window, and if the bins at the side of the house are a bit of a mess - well, that's urban foxes for you, not decadence.

But the kitchen. That's where the clues lie. Open the cupboards and ... yup. No canteen of cutlery. No dinner service. No cut-glass fruit bowl, still in its box, on the top shelf. No dinky salt-and-pepper shakers. No gravy boat. Not even a Philippe Starck juicer. The conclusion is obvious, but, please - lower your voice: we're not married.

I can be scornful - all that clutter, all those cabinets (when we moved house, the childless but married couple who bought our old one couldn't believe how we'd managed) - but I do long for a Philippe Starck juicer. And it must be nice, when you have people round, to bring out some knives and forks from those lovely velvet cushioned cases and see your face for a moment in their shiny, rounded silver handles. I know people get married for lots of reasons other than religious ones: to make a point of their commitment, to provide stability for children, to go on nice, long honeymoons, to take advantage of the tax and pension benefits, to stand up and declare their love for each other in front of the people they know. But, to be honest, I find it hard not to think about the presents.

Maggie, the character in my new novel, Having It and Eating It, isn't married either. She and her partner live together and have children and left to her own devices she would have had a church ceremony and a frock (Fifties puffball style, classic with a twist) and a cake and a party in which the best man got off with the maid of honour and there were lots of speeches in which people said nice things about her. But Jake, her boyfriend/partner/husband-type person (none of these names really does the job, which is one of the problems) has never wanted to get married. "Who needs a piece of paper?" he says - as people do. In lots of ways the two of them are about as conventional as you can get, but there's just a little bit of him that wants to prove he isn't.

What interested me when I was writing the book was the inequality of the situation - Maggie's needling sense that Jake doesn't love her as much as he could, that things between them are somehow unfinished. I wondered what it would be like not to be married and yet want to be and how that affects your reaction when the relationship is put under strain. When Maggie gives up work to look after their two small children, when Jake's hours get longer and longer, when he starts coming in smelling of office party while Maggie smells of nappy wipes and Calpol, her insecurity is stoked by the fact that they're not married and, finally, she uses it as an excuse to behave badly herself. By the end, out of remorse, she comes to think that maybe it is just a piece of paper after all. She may not be in a married couple, but she is in a family.

People ask you all the time why you're not married, as if suspecting there must be some Big Reason. In my case, there isn't. I'm a lapsed Catholic, so I would find the church bit hypocritical, but I'm not ideologically opposed to marriage as an institution (for one thing I'd like to know that my boyfriend/ partner/husband-type-person has equal rights over our children; to guarantee that, unmarried couples must sign a parental responsibility agreement). But you can start off meaning to (get married, that is) and then life picks you up and carries you along and you're too busy buying a house, or too pregnant, or too milksopped, or too tired, and then one day you realise you're still not married and that, in a small way, that's become part of the person you are.

Anyway, I'm too old now. Fifties-style puffball? It would have to have a big twist.

Having It and Eating It is published on 14 February by Time Warner.