A woman who is 'desperately unhappy' in her marriage has been refused a divorce by a judge. Tini Owens, 65, wants a divorce on the grounds that her marriage has broken down irretrievably. However her husband Hugh disagrees and says there are a few years in it yet. She has appealed.

Cases like this are extremely rare in that very few divorces are contested in this way. There are only five legal grounds for divorce – adultery, unreasonable behaviour, desertion, two years separation if both agree, and five years separation if only one spouse wants the divorce. Being 'desperately unhappy' is not one of them. Should the court of appeal turn her down, her options are either to find evidence of unreasonable behaviour or to wait five years.

According to former high court judge Sir Paul Coleridge, chairman of Marriage Foundation, divorce law in the UK is effectively only fault-based on paper. Provided both parties want the divorce, which is almost always the case, one party files and ticks one of the boxes. Roughly two thirds of divorces are granted to wives. Roughly half of all divorces are granted on the grounds of unreasonable behaviour. Cases that go to court are invariably then a matter of sorting out money and children.

Having gone to the trouble and vast expense of taking her husband to court in this way, it seems extremely unlikely that this particular marriage could ever be reconciled. One notable divorce lawyer described the need to prove fault to a judge 'beyond archaic'.

But is it? Should 'desperately unhappy' be grounds for divorce?

In a new study that we published earlier this month, Professor Steve McKay and I looked at what happens to unhappy couples. Out of a sample of some 10,000 new mothers who had babies in the year 2000 or 2001, five per cent said that they were 'unhappy in their relationship' soon after their child was born.

By the time their children were aged eleven, 30 per cent of these unhappy mums had separated from their partners. But of those who stuck it out, 68 per cent now said they were 'happy'. Only seven per cent said they were still 'unhappy'.

The number of women who remained stuck in an unhappy marriage for a decade or more was therefore extremely small, fewer than 25 out of the original 10,000 mothers. It is possible that even these poor souls had been happy at some stage along the way. We don't know.

What is clear is that two thirds of those who stick it out eventually find happiness.

I know this situation all too well myself, having found myself in an unhappy marriage and on the brink of divorce some 22 years ago. At that time, my wife Kate and I had done the classic thing of 'growing apart' soon after our first two children were born. Our recovery began with a letter from Kate that brought me to my senses and caused me to realise I needed to make my marriage work for Kate. We've now been married 30 years and are extremely happy.

In our case we never got anywhere near the stage of consulting lawyers. What the law did or didn't allow had little bearing on our situation.

But what if a genuine 'no fault' divorce law was introduced so that couples could divorce quickly and easily simply because one of them is unhappy?

Our research highlights the risk of this approach. Unhappiness is rarely permanent. Given time, most couples emerge from periods of unhappiness. Previous American research that looked at this has found that people either work at it, go on a marriage course, change their attitude or change their circumstances. Either way, most find happiness. That's good news for them and for their children.

The couple in this court case are different to the new parents in our study because they have been married 39 years.

But who knows. Maybe in refusing their divorce, the judge has thrown them a lifeline. Maybe the husband will step up. Maybe the wife will give him another chance. It's unlikely, I admit.

Yet one thing I've learned from years of teaching couples about how to have a happy marriage, from supporting couples in trouble, and from my own marriage.

It's never over until it's over.

Harry Benson is research director of Marriage Foundation and co-author, with his wife Kate, of What Mums Want (And Dads Need To Know).