Will you be lonesome tonight?

Haughty, power-dressed and still running on adrenalin after a 12-hour day in the office, young professionals in modish suits stalk the aisles of late-opening supermarkets looking for comfort food - and usually comfort alcohol as well - with which to settle on the sofa and relax for what little is left of the day.

These, you would think, are the winners of the Nineties, the favoured few who have survived recession, unemployment and redundancy. They are young and well-qualified enough to take their pick of jobs. If anyone can be said to "have it all", it must surely be these 25- to 35-year-olds. And they do have nearly everything - except intimacy. Loneliness is the price they pay for their high-flying lives.

It's not new for the young and single to exert a powerful influence upon our culture, mainly through music and their sexual mores. They have had that influence since the Fifties. But two things stand out about the singles of the Nineties. The first is that their influence is pervasive and powerful. It is not confined to music; it affects everything from the kind of houses that are being built to the growth of dating agencies, from the types of food that stock supermarket shelves to the kinds of holiday now on offer.

The second distinguishing feature of the singles of the Nineties is that they are not hopeful. In the past, single young people seemed to hold out the promise of revolution and change, a better future. They were idealistic and usually optimistic. Today's young singles are stressed, over-worked, and often simply sad. They lack intimacy and the trust that goes with it. They avoid emotional commitments. They seem spiritually at sea.

Take what is often most important to them: work. They operate in the high-pressured world of multi-skilled people, in delayered organisations. If they are self-employed, they must devote themselves to building up their business. If they work for an employer, they cannot expect to stay with the same company for decades. A few years at most and they are on the move in search of more money, better prospects, higher promotion.

The pursuit of money and ambition is used as a justification for their absurdly demanding working hours. They work to earn, but also because it provides the point to their lives. They get anxious when they are away from work. They go nowhere without their mobile phones and laptop PCs. "Technology was provided to buy more time and relaxation," said one tired young woman. "But now we are accessible 24 hours a day. Far from enjoying more leisure, I find there is no escape from work."

Caroline Gielnik, a stress expert at the the Institute of Directors, believes that working late often forms a comfort zone for lonely people. She regards work addiction as a form of obsession, which lies in a more deep-rooted fear of intimacy. So when they leave work, these young, single professionals are at their time of maximum exposure, when the gaping emotional hole in their lives opens up before them.

I watched three bachelors in a central London Sainsbury's just before 9pm last week. They were buying food targeted at people too tired or lonely to cook for themselves, and with nobody at home willing to cook for them. One man, Roderick, was queuing at the check-out to pay for a French stick, a chunk of cheese, a mango, a box of strawberries, a six-pack of beer ... and four tins of cat food.

A man I accosted in Marks and Spencer at closing time gave his name as Michael, and said he was a corporate banker. He was buying a bottle of cheap white wine and a takeaway supper. He said, "Meeting women at work is a minefield of office politics and political correctness. It's much easier and safer and less complicated to come here and buy for one. Hell, if I want company I can watch Northern Exposure or Friends." In any case, he said, since he had to get to work by 7am he was usually in bed well before midnight.

In a recent Mori opinion survey of their age- and income-group, nearly a third agreed with the statement: "I don't have time to spend cooking or preparing food." In the past 10 years, this has created a massive market for cook-chill TV suppers warmed in a microwave.

Nick Herbert is a food consultant at Marks and Spencer. Lasagne, he said, was the store's most popular "instant" dish, followed by the complete Chinese meal for one. But most striking, he suggested, was the sharp increase in sales of single-serving puddings, sticky toffee pudding being the most popular, followed by syrup sponge. Stressed and lonely individuals were seeking consolation in "treats" and comfort food of the kind their mother might have made, or food that might make them feel they were having an exotic evening out.

Food is not the only area where the culture of the single is rampant. In 1993, more than a quarter of UK households consisted of just one person: nearly twice as many as 30 years ago. The increase does not come from the ranks of the old, the mad, or the eccentric; they have always lived alone. There is a new category of solitaries made up of attractive and desirable young people. The fastest-growing section of the housing market is made up of young men buying homes in which to live by themselves.

They are addicted to style. The amount they spend on clothes would appal their parents and stupefy their grandparents. It is all part of a relentless, even obsessional pursuit of style. The same care and concentration that attends to the cut of a collar is lavished on their homes and furniture, down to the pedal bin in the bathroom (cylindrical stainless steel, Conran Shop, pounds 69). They set the agenda in fashion, the media, food, restaurants and clubs. Their influence spreads far beyond their ranks.

Their modishly empty warehouse flats or houses converted from a redundant church are featured in style magazines; the Sunday supplements invite them to list their three favourite restaurants - the more eclectic the better - or 10 favourite books, or six best cars. They buck the trend towards greenness and a social conscience. They don't feel guilty. They are not as shamelessly flash as their yuppie predecessors in the Roaring Eighties. They are less gregarious, more private; less extravagant, more discriminating; but their lives look a lot less fun. Certainly they dress more austerely, although those high-buttoned sober shirts of rigorous cut and neutral colour cost just as much as did the exuberant patterned numbers from Paul Smith 10 years ago.

They work in order to earn and earn in order to spend. Solitary high- spenders have been immensely profitable for the purveyors of many services undreamt-of 20 or 30 years ago. Takeaway meals, lonely-hearts columns, men's "lifestyle" (not "girlie") magazines; late-night shops; video hire; supermarket wines; cookery classes for men, body-building classes for women; dating agencies, singles holidays, cheap air-travel, sexual tourism, surfing the Internet ... all these benefit from a vast market.

They value all these objects as an opportunity for self-indulgence ("presents for the house"); self-advertisement ("look how discriminating my taste is; clock how much money I've got"); and self-definition ("I am the sort of person who can afford these sort of tricks"). But this display hides the absence of any deep emotional commitment.

For in all this consuming, what they are unconsciously doing is buying parenting, in the form of food and treats, to make up for the absence of the reassurance that parents - or a spouse - would otherwise supply. For despite being in work and earning good money, loneliness is prevalent among them. They disguise it all too well by joining sports clubs and gyms, roller-blading, eating out at weekends or going clubbing in shiny clothes.

Naturally they don't call it loneliness, which they regard as a stigma - the lonely always do. They define living alone as the pursuit of individuality. Yet loneliness is the most obvious and predictable consequence of late marriage and even later child-bearing.

It is not just that they find it difficult to establish relationships based on real intimacy. They even find meeting people difficult. Relationships with colleagues of the opposite sex - potential partners, cohabiters or spouses - are complicated by political correctness. Except in a few die- hard, macho City office environments, it is more prudent not to flirt.

The number of people using introduction agencies, as marriage bureaux prefer to be known, has doubled in the last 15 years, from around 50,000 in 1980 to 100,000 this year. There are an estimated 200 in the UK, of which some 25 per cent close every year, usually having taken the money and run, trusting to the embarrassment of clients not to pursue publicity. Many use accommodation addresses and are untraceable once they have folded.

Given these risks, many single people prefer to place an advertisement in one of the lonely hearts columns that have grown tenfold in recent years. Those in the up-market national newspapers have proliferated, catering as they do for an audience of young ABC1s.

There is no doubt that these single high-pressured lives come with an enormous downside: the aching loneliness that comes from lack of commitment. Asked by Mori in 1993 to list what they most disliked about being single, 37 per cent of single young people cited loneliness; 16 per cent sleeping alone; 15 per cent the lack of emotional security; 9 per cent felt unprotected; 8 per cent feared they would never have children; 7 per cent hated cooking and eating alone. It forms a bleak catalogue of the terrors of the single life, in which it is hard to recognise the joys of bachelordom so ardently recommended by Cosmo and GQ.

It is my theory, based on dozens of conversations, that the single greatest reason why this generation avoids commitment is the failure of marriages in their parents' generation. They have become suspicious of commitment, worried that it will cramp their style and ambition.

When I married in the early Sixties, we were both 22, and no one, least of all us, thought twice about it. Most of my contemporaries were walking up the aisle at about the same age. That was just before things really began to swing. Since then we've had the Pill, flower power, women's liberation, feminism, equal opportunities legislation and political correctness, all of which have done their bit to alter the way the sexes meet, mate and relate.

Today's young are marrying later than their parents, if at all; later than a generation unencumbered by war has ever done. When my stepson married at 20, the general reaction was one of astonishment. "He's how old? And his girlfriend is 21? But they're so young!" In that year, 1992, the average age of first marriage for women was 26, and for men, 28.

One-third of this age-group cohabit, most of them claiming that their pair-bond or family unit is at least as secure as their parents' marriages. They need no formalities to undo the relationship. They decide between them who gets the flat, the furniture, the cat, and the CDs, and go their separate ways.

By the early Nineties, the UK had the highest divorce rate in the European Union. The word "family" has taken on a new connotation. It does not necessarily imply a blood link; instead, the family network has become a living reminder of past relationships and love affairs.

Permanence and good example, let alone religion, have played little part in their lives. It is no exaggeration to call these 25- to 35-year- olds spiritually lost and dislocated. Those too sceptical or too intelligent to join one of the cults that spring up like dragons' teeth are resolute atheists. Most are driven by work, ambition and money. They have pleasures and desires, hobbies and pastimes, but little by way of what someone older would recognise for spiritual ballast. They fight alone in a competitive world.