Marriage is out of fashion, but it shouldn't be

"How's married life?" People ask it in a slightly mocking tone, as if it's rather quaint to think that married life should be any different from unmarried life. One year in, however, I've been surprised to find that it is different - in a good way.

This idea is increasingly out of fashion. Nearly half of British babies are born to unmarried parents. And now, in a strange twist on the gay rights movement, straight couples have started demanding the right to form civil unions instead of marriages. One test case on the matter has just found its way to the Court of Appeal.

The couple bringing the case want a civil union in order to benefit from the purely functional, legal advantages of marriage without any of the other baggage that they imagine it brings. It's unfair, they say, that gays can obtain civil unions and straights can't. Girly girls have ruined marriage, the woman of the couple implies: "There are girls who grew up thinking about their wedding dress but I increasingly felt that outside of the fairy-tale of it all, that I do not feel like a wife. It just doesn't square with me," she told the BBC.

Well, I suppose they should be allowed to do what they want, but it's a deeply depressing idea. The joy of a union between two adults is amplified by the symbolism and cultural importance of marriage. Without it, there's not much difference between getting married and filing a tax return.

Weddings don't need to follow a formula: a large dress, a cake, a drunk uncle (though as it happens, my wedding had all three). I've been to weddings small and large, formal and informal, town and country. I've witnessed the traditional Christian ritual and secular versions, including one in which the congregation, asked to promise support for the marriage, said: "We do." But I have never heard of a marriage certificate obtained for legal reasons, whether it's a visa or an inheritance, that didn't go badly wrong.

There is a reason for that: a wedding isn't primarily a legal matter. It's a public commitment, a rite of passage and a ritual that creates a type of community between family and friends on both sides. The existence of this community is manifestly positive for its participants and helps a relationship survive.

Marriages last longer than cohabitations. I don't believe that this is just a correlation. Even before a wedding, it strengthens a relationship by forcing a couple to make an active decision about the future. Afterwards, it lends an air of permanence that is constructive for working out problems. It can transform an extended adolescence into adulthood, in which rights and responsibilities are taken more seriously.

There's also a knock-on effect for a whole community of friends and family. Weddings create direct relationships - new aunts, uncles, nieces and nephews. They bring together friends from different countries and walks of life. They impose duties on others too: it's easy to dismiss a friend's annoying boyfriend, but once his status is cemented as a husband, everyone has to try to get along. All of this is why "married life" feels different.

"Ah," the cynics say, "but no one needs to get married for all of that stuff. They can have children." To be sure, there's no greater commitment than a child. But a child should not be the glue that holds a couple together. Couples should have a relationship that exists separately from their offspring. And while it can be noble to stay together for the sake of a child, it's no substitute for a happy marriage.

Its detractors have a litany of historical grievances. They claim that marriage is irreparably tarnished by a past of sexist laws, which forbade divorce, treated wives as property or gave husbands the right to rape them. This line of argument is rather silly. Should I not pay taxes because feudal lords used to exploit their serfs? Should Britain avoid trading with West Africa, because we once exported African slaves? Should we abolish prisons because their conditions used to be so deplorable? Of course not.

The evolution of marriage is one of the great, reforming success stories. It's proof that societies can realise the error of their ways and fix them. There are few more visible signs of women's legal liberation than the idea that a marriage occurs between two equals. Feminists should be especially enthusiastic about endorsing these improvements - by marrying, for example.

At its core, there is a barbarity to the idea that marriage is outdated. The law already allows couples to marry with minimal ritual and only two witnesses. What possible reason is there to strip it down further by replacing it with the explicitly drab functionality of civil union? Modern life is depleted enough of meaningful rituals without attacking one of the last and most joyful of them all.

So marry or don't marry: it's fine by me. But don't avoid marriage for some foolish reason, like the patriarchy or because it's stuffy or because you don't want to wear a big dress. The law now treats us all as responsible adults. We should act like it too.