It is tempting to put this down to the problems of glitzy and glamorous relationships, the inevitably heady chemistry of fame, too much travel, prima donna egos and overwork. But the truth is that what is happening to famous career couples is little different from what is happening to many ordinary people.
Charles Handy puts it well in his book The Age of Unreason (Arrow, pounds 6.99). It is rare, he says, for career couples to have happy and lasting relationships precisely because so much energy is put into achieving success at work. For a relationship to thrive it requires a lot of investment of time and energy. Often, public success for one partner depends on the other being altruistic and caring.
Not long ago, of course, this was the norm. But today most households have two earners. Few women are content any more to be the power behind the throne, the shoulder to cry on. Instead they want the bright lights and the sense of identity that comes from a good job. It is little wonder that surveys show that schoolgirls now talk of wanting careers first and family second and that they are eager to take advantage of the opportunities not available to previous generations of women.
For many women the desire to achieve at work is almost overwhelming. Relationships have to fit around work, not the other way round. As one professional woman in her late twenties said, "Sometimes I feel I am striving and driving so hard for a career, I forget there are other things in life which are important."
Many - especially professionals - are in geographically-strained relationships, struggling to maintain contact with long-distance phone calls and snatched weekends away. Although they are aware their relationships are suffering, many say that if push comes to shove, they would put work first.Perhaps because work has become the source of so much personal gratification and the place where so many people spend such a lot of their time, it is not only a contributory factor in relationship breakdown, it is also the place where many clandestine relationships are started.
Taking account of another person's ambitions as well as your own is bad enough. But the strains on relationships are amplified by other factors. After a long decline throughout this century, working hours began rising in the Eighties and have continued to climb in the Nineties. The lunch hour is a thing of the past and the Britishwork the longest hours in Europe. The "time squeeze" that haunts people's lives is clearly putting relationships and family life under strain. No wonder that as many as 80 per cent of working mothers and 88 per cent of working fathers aged between 18 and 34 told a recent survey by Mori Socioconsult that they want to spend more time with their families and would welcome greater flexibility over their working hours.
Perhaps because of this time pressure, there is a new mood to the Nineties which is in stark contrast to the go-getting work-oriented Eighties. A book published this week, After Success by Professor Ray Pahl (pounds 12.99, Polity Press) argues that many successful people are now re-evaluating their achievements and seeking fulfilment beyond work. Having reached their forties and fifties, they are all too aware of the heavy price they have had to pay for their careers.
It is not only the middle-aged who are questioning their values. A younger generation with high expectations of fulfilment at work want to fulfil themselves outside of work as well. Because they are growing up amid endemic job insecurity, they are bound to question just how wise it is to invest all their emotional energy in work when jobs are becoming so much less reliable. Many, too, are aware of how many mistakes their parents made, especially in terms of relationships, and that achievement in one domain was matched by failure elsewhere.
Perhaps because of this the young are redefining the meaning of success to encompass the private as well as the public sphere, with many finding identities through personal relationships - networks of friends and family - as well as through work. It is not surprising that many of them flock to see films such as Slackers, Reality Bites and Before Sunrise which catch the mood of a generation searching for meaning in their lives in a world where the rules are being rewritten.
Across the world this questioning of work, success and personal fulfilment is visible. Even in Japan, commentators lament the changing work ethic of the "grasshopper" generation who are now refusing to put in hours at work that are not mandatory and who organise their lives around the three Vs: villas, visits and vistas.
It would be marvellous to think that in the Nineties we were seeing a shift towards a more balanced work ethic with renewed emphasis on relationships and family life. But don't hold your breath.
For all these signs of change, it is hard to be wholly optimistic. Perhaps our greatest obstacle is that as a society we still define success by what we do, rather than who we are. Our culture lauds the public world of work much more than the private world of relationships and family life. We still have different standards of success for women than for men, and women pay a high price for trying to have it all.
I wonder whether there is another way. Many career couples are trying to work together - in restaurants and shops and consultancies and law firms - to contain the pressures. With the advent of the flexible labour market, the family firm may well be reborn, with more people linking the home to the workplace in ways that were once quite common before the advent of the industrial society.
That is perhaps why Thompson and Branagh's relationship has hit problems. Once the epitome of the working-together couple, recently their careers and relationship have become increasingly divorced from each other, no longer intimately connected. Perhaps inevitably, distance meant that they stopped working hard enough at the relationship.
Whatever the causes, the very public playing out of the private dramas affecting our golden career couple is a timely reminder of how difficult it is to achieve the right balance between success in one sphere and failure in another.