For better for worse, for richer for poorer, in sickness and in health, till death us do part. Golly! No wonder we women, sturdy realists at heart, weep in the pews at church weddings. Promises so vast make us dizzy with vicarious hope and terror: for all the flummery, this is more than a romantic piece of theatre. It is a blind promise of heroic proportions. If this is a fairytale, it is one where the parties undertake to spin straw into gold or drink the sea dry.

We live long these days: decades of personal change and varying fortune lie ahead of the bride and groom, probably complicated by the arrival of children and (even more disruptive) their eventual departure from the empty nest. The resonant words are not spoken in civil ceremonies, but even so they hover in the air over every bride and groom, however shopworn. For better, for worse. Marriage is supposed to be proof against change, decay, temptation and boredom. If, that is, you really mean it.

Once, secular law assumed everyone did. Divorce was made possible but difficult for ordinary citizens in the mid-19th century, and easier through the 1920s and 30s, although you still had to prove adultery, cruelty, insanity, desertion or gross misbehaviour. It was not enough just to be bored. But 40 years ago the 1969 Act ruled that separation and “irretrievable breakdown” would do, and that nobody need admit or prove fault. Since then divorce has become fully accepted, socially undamaging and hairily frequent. The Office for National Statistics reckons that 45 per cent of new marriages will end in divorce, mostly before they hit the ten-year mark (after 20 years, only one in six of us will fall dismally apart like a wedding cake left out in the rain). We put little stigma on bad choices, bad judgment, bad luck or bad behaviour. We are tolerant.

In the light of this reality, a significant change is brewing. Break-ups can’t be made cheerful, but they could be prevented from becoming rip-offs. In the US, much of Europe and in Scotland prenuptial agreements about assets are legally binding. In England and Wales, they are not. Yet a strong tide is running: five years ago a survey found that nearly half of us would favour prenups, with women marginally keener than men (told you we were the realists). And now a big law firm says that the number of such contracts has increased tenfold, doubling last year: this despite their being unenforceable. It is as if people were — independently of government — anticipating and expecting legal change.

They seem to be right. The Appeal Court surprised traditional opinion in July, in the case of the heiress Katrin Radmacher. It overturned an earlier court’s decision to ignore her prenup contract and give her husband of eight years £5.8 million. Now he has to make do with one million cash, plus a £2.25 million loan for housing, to be returned when the youngest child leaves home (and presumably no longer needs such ritzy access weekends). Now, the lower courts will have to think harder before ignoring these contracts. Moreover the Tory party — formerly branded as the party of marriage, family, and brown Windsor soup — has come right out and said yes, prenups should be binding.

Well. I am a romantic and a wife of 30 years, fingers crossed, and on record as a believer in marriage, civil partnership, stability, fidelity, all that stuff. For a long time I sniffed at prenups: a Hollywood habit, redolent of Zeta-Jones and Douglas (she is said to have signed one at his insistence after his first wife copped £44 million). But the British divorce courts, sweet romantics, have enabled too much greed and injustice at every financial level: huge fortunes handed over to childless and adulterous partners, rich men and women taken for a ride, trusting and innocent individuals exiled from homes they bought unaided. As the comedian Lewis Grizzard observed: “I don’t think I’ll get married again. I’ll just find a woman I don’t like, and give her a house.”

I suppose the trend had to grow after 1969 and “no-fault” divorce: many a bitter chap will inform you that it is now possible for a strange man to annex your wife, children, house and half your money even if you never put a foot wrong.

“Why,” asks one childless and cuckolded spouse, “must I buy my way out of a brief marriage which I wholly financed?” It hits women too: one, unwillingly childless and emotionally bruised from IVF failures, mourns the fact that she must sell the old family house and move, complete with her ageing father, in order to fund the court’s belief that her husband and his pregnant mistress deserve a comfy lifestyle.

None of us — well, hardly any — marries with divorce in mind. Yet divorce happens. Those who deplore prenups say that they create a toxic sense of the relationship being on trial, that even with safeguards for children and disability they are a nasty, grasping foreign invention that undermines the seriousness of marriage. Yet the more I think about it, the more I approve. Now that nobody listens much to parents or vicars, marriage has become a lobster pot: easy to get into without much thought, painful to get out of. The engagement period, which might be better spent in discussion of the shared future, is now more likely to be devoted to spending indecent sums on a vast party, designer dress, thousand-pound cake and dream honeymoon. Not to mention the creation of a slightly revolting wish list of presents.

Sitting down to face the cool terms of a prenup might be just the thing to teach you a bit more about your beloved. It might remind the lovelorn that this is not just a dream come true: it is the creation of a home and a life, not to mention an undertaking to adapt your habits to suit another person’s happiness.

One lawyer has claimed that marriages with prenups actually last longer because people are taking “a practical attitude and not going into it with romance eyes”. I can see that now. But 30 years ago I might have needed help to see it.

I can also see that if we do nothing, more and more high-earners and homeowners will start running scared and deciding never to risk marriage at all. Which would be a shame.

It’s a good gig.

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