The Beckhams' marriage is in the spotlight following allegations of David's affair. As they to try patch things up on holiday together in Switzerland, Women's Editor Christen Pears asks whether a relationship can survive an affair.

STAND by your man and show the world you love him... attitudes to marriage have changed since Tammy Wynette sang her way to the top of the charts in 1968 but the world is waiting to see whether Victoria Beckham will be covering the famous hit.

The former Spice Girl flew to Switzerland on Sunday as the News of the World published intimate details of an alleged relationship between her husband David and his former personal assistant, 26-year-old Rebecca Loos. The England captain dismissed claims he had an affair as "ludicrous" and joined his wife and sons on holiday yesterday. But the rumours just won't go away.

Whether they are true or not, the couple certainly have a lot of talking to do. The Beckhams have spent a considerable amount of time apart in recent months, with Posh working with rap star Damon Dash in New York and Beckham remaining in Madrid. The once-golden marriage is beginning to look tarnished, but will it survive?

There are plenty of couples whose relationships survive an affair but there are just as many whose don't. For every Mary Archer or Hillary Clinton standing loyally by her man, there's an Alex Best or Jerry Hall giving her unfaithful spouse the elbow - but not always in the first instance. Some try to make the marriage work but find it impossible.

After eight years of trying to cope with George's drunken, womanising antics and nursing him through his liver transplant, Alex Best finally gave up last year when the notorious hell raiser picked up a girl in a bar. Jerry Hall was well aware that Mick Jagger was no angel, turning a blind eye to myriad affairs but the last straw was his fling with Brazilian model Luciana Morad, which produced a son.

WE live in a society where more people are having more sex with more partners but when it comes to committed relationships, 80 to 90 per cent say that extra-marital sex is wrong. And despite increasingly liberal attitudes, fidelity is still seen as one of the top three ingredients of a successful relationship.

A survey carried out three years ago by Relate, the relationship counselling service, found that two thirds of people said they could not forgive their partner after an affair. But when faced with the reality of an affair, they often feel differently.

"The common idea that everybody breaks up is simply not true," says Julia Cole, couples counsellor and author of the book, After the Affair. "They often take into account practical issues like caring for children or the resources they may have invested jointly and decide to stay together. The problem is rebuilding the relationship once you have made the decision."

Relate deals with hundreds of inquiries from couples who want to give their relationship another chance and according to the organisation's help sheet, the first step is understanding why it happened in the first place. It may be the affair itself is the product of existing problems and the relationship is already too damaged to survive.

Experts have identified three major factors that place a relationship at risk of an affair: boredom, low self-esteem and relationship problems, including rejection and anger.

If allegations of David Beckham's fling with his PA are true, we don't have to look very hard for the reasons. The England captain has been living virtually alone in Madrid while his wife has concentrated on her career in England and America.

Julia says: "If you are in a really happy relationship, you don't seek an affair with somebody else. I often say an affair is the symptom and not the cause of a relationship breakdown. You have to look at the illness behind it."

MAKING the decision to stay together is the easy bit. Making the relationship work, and particularly building up trust, is far more difficult.

"We don't know whether this is true about the Beckhams or not but the problem is not what the person who has the affair has done to the other one sexually speaking. A lot of people whose partners have had an affair say the worst thing is the sense of betrayal," says Julia.

Affairs are not just about sex, as the growth of Internet affairs shows. Some argue that it's not a real affair without sex but relationship experts say that any intimate activity that breaches a partner's trust is an affair. Regaining that trust can take months, and even years.

"Some people never recover from it. What you are looking at is a bereavement because the marriage or relationship has died and you've got to start again.

"People do recover from it and often say their relationship has been strengthened but what you often don't see from the outside the sheer emotional hard work that has gone into. It is possible but it's never straightforward."