From childhood, South Korean pop star Soyou dreamed about getting married, having three children and living in a house filled with the aroma of cooking.

But like so many of her fellow female citizens, the 34-year-old singer - who became one of her nation's biggest stars with heartfelt songs about love, relationships and romance - has now abandoned such traditional ideas.

In a candid interview last month, she disclosed that she decided during Covid that she did not want to bring a child into the world and had ruled out marriage. 'If I don't want children, why marry?' she said.

Many other South Korean women are asking the same question - with the result that this highly successful Asian country is confronting the world's worst fertility crisis and arguably the most ferocious gender wars among younger generations.

Behind the nation's glossy image - with its famous beauty culture, films and music - lie sharp divisions and dissatisfaction for many women both at home and in the workplace over some of the most stark gender inequalities of any developed country.

The disgruntlement has sparked relationship boycott groups with thousands of women vowing to stay single forever - symbolised by the 4B movement, whose members pledge to reject marriage, childbirth, dating or heterosexual sex for life. 'We just want to build a world where women can live free of men,' says one activist.

South Korea's fertility rate - the average number of babies born to each woman - is just 0.8, provoking profound fears for its future since this is far below the 2.1 level needed to ensure population stability without immigration.

The nation has become the most striking example of the global decline in birth rates, a decline that has left two-thirds of people living in countries with fertility rates below this critical level.There is concern that half of South Korea's rapidly ageing population will be pensioners within three decades, making its population the oldest in human history.

There are even alarmist predictions that its population risks being almost wiped out by the end of this century. Kindergartens are being converted into care homes while at least 150 elementary schools had no new pupils when the academic year started last month. The number of children entering education in the capital Seoul - home to a fifth of the population - has fallen eight per cent on the previous year.

Sales of prams for dogs now outsell those for babies. And with so many childless households, the number of registered dogs and cats - child substitutes, perhaps - has almost tripled over the past decade. 'We're so busy right now,' said one firm making £850 pet buggies.

Vila, 23, a design student I met in Seoul, told me she never wanted children or to marry, preferring to live alone with her pet beagle. 'My life is good enough already. A dog lives for maybe 15 years but a child is forever.'

Jin Haerin, 24 agreed there was a widespread reluctance to have children. 'My older sister is determined not to get married because she doesn't want children. I am not sure if I want children either,' she said.

Such views make South Korea - which has spent an astonishing £200billion over two decades trying to solve its fertility crisis - a testbed for the problem of falling birth rates afflicting so much of the developed world.

The latest data for England and Wales shows fertility rates plunging from 1.94 in 2010 to a record low of 1.41 in 2024, sparking fears over the funding of health and welfare systems from a reduced younger workforce as our society gets older. Scotland faces greater problems, with a rate of 1.25.

Spain, Italy, Greece and Poland are grappling with some of Europe's worst fertility problems - all with lower rates than Scotland - while the US disclosed this month that its birth rates have dropped almost one-quarter in just two decades.

But it is South Korea where the problem is greatest. Many of the concerns facing its women are familiar to us in Britain, such as soaring housing costs, workplace sexism and the trade-off between a career and motherhood.

Yet in South Korea, many of the pressures are more extreme. It is the world's most expensive place to raise a child. Its women are the most highly educated of those in OECD countries, yet endure the worst gender pay gap and share of household duties. Korea also has the longest working hours of any advanced nation.

Many women feel they are presented with a choice - to have a career or a family. And they are choosing a career.

This is a country that evolved with unprecedented speed from war-torn poverty in the 1950s into a cultural, industrial and technological powerhouse, yet in terms of gender parity and domestic division of labour it remains in the dark ages. Six decades ago the average Korean woman had six children - but now huge numbers are opting to reject men along with traditional expectations over their role in society.

Among them is Moon Young-one, 24, a maths tutor and leader of a rapidly growing group of 4B followers called Wolves in the Hell (WITH), which boasts 550 members and claims to be one of many such communities.

'It is really hard to survive as a woman here,' she said. 'Our movement is not about rejecting men - I don't want to spend my limited time alive hating men - but against a patriarchal system. It's about cherishing women. And it is ok not to have a man.'

4B is shorthand for four Korean words that start with bi - meaning 'no': bihon (rejection of marriage), biyeonae (no dating), bisekseu (abstaining from sex) and bichulsan (refusal of childbirth). Many other women declare themselves 'bihon', denoting their choice to remain single forever.

This movement flared up in the wake of outrage after the 2016 murder in a Seoul subway station lavatory of a 23-year-old woman by a man who told police he felt 'ignored and belittled' by females. Another subway station murder - of a 28-year-old stabbed by her long-term stalker three years ago - ignited fresh dismay and fury.

The concept of 4B has spread to other countries on social media while there has been a brutal male backlash here in South Korea. 'Discarded bitch' was among responses to Soyou's interview in one dark corner of the manosphere, with a teacher boasting of using his phone to film and upload non-consensual sex acts with women.

South Korea is also awash with digital sleaze. A spate of sordid scandals revealed men sharing footage of deepfake pornography that attached girls' faces to AI-created videos; of women blackmailed into sharing intimate content; even of young girls secretly filmed in changing rooms and toilets. 'This is a cruel place to be a woman,' declared author Mingyeong Lee, a founding member of 4B. 'If we give birth to girls, they'll be neither safe nor happy.'

WITH activists insist their movement goes far beyond a sex strike, citing its backing for protests, support for abuse victims and social events. 'We aim to create a bihon community or town - that's the ultimate goal,' said Moon.

When I asked during our meeting in a cafe near Seoul if this would mean having nothing to do with men, the activist replied 'that would be nice' with a smile.

She explained how she grew up in a conservative region where men and women would eat separately. Older relatives would ask why she bothered to study since she was expected to marry and devote herself to raising children.

Yet she said her own parents divorced when she was young 'so I never had much fondness for the idea of marriage', then after discovering feminism as a teenager found that the supportive 4B movement 'felt more like a family than my actual one'.

Moon - who last had a boyfriend during her schooldays - told me about being stripped and sexually abused at a young age by a male relative, then burying the incident in her mind until discovering feminism. Like many 4B followers, she cut her hair short aged 18 - a bold statement in a country with such a strong beauty culture, the world's skinniest women and where one in five female citizens have had cosmetic procedures before the age of 40.

'The beauty industry puts pressure on women to look beautiful but also enhances a culture of women hatred. It makes many women self-conscious, concealing what is really needed for Korean women: safety, money, caring more about living your life.'

The 4B movement is related to other Korean feminist trends that reject traditional beauty standards, yet Moon admitted feeling terrified when cutting her thick black hair. 'I feared people look at short-haired women as weird and abnormal,' she said.

Such concerns are not groundless. In one high profile case, a shop worker was badly beaten by a man simply for having short hair. 'Feminists deserve to be beaten,' he shouted during the attack, which left his victim with hearing loss. And a female archer who won two gold medals at the Tokyo Olympics was subjected to vicious online abuse from angry men who accused her of being a feminist for having short hair, although she said she had cut it for 'convenience'.

Another 4B activist said women with short hair were routinely 'labelled as mentally ill, harassed and even physically assaulted because they look like feminists'.

It was after the US Supreme Court reversed the landmark 1973 Roe v Wade judgment legalising abortion in 2022 that 4B went global. Donald Trump's re-election as President two years later only boosted its appeal. Some American women declared support online while the actress Julia Fox - who declared in 2024 that she had been celibate for two-and-a-half years - called for the founding of a similarly radical US group.

The movement reflects the frustration felt by many young South Korean women, caught in the crush between cultural conservatism and modern mores that one Nobel-winning economist believes to be a key factor in the nation's low birthrates.

Claudia Goldin, a Harvard expert on gender, pay and labour markets, highlighted data last year showing they spend almost three more hours per day on household chores than men. She argues that while rapid modernisation improved education and job prospects, domestic expectations remain unchanged.

One survey last year revealed married women in South Korea are almost three times more likely than men to say they would not want to wed again if given the chance of a new life. Other studies have found young women to be much less interested in dating, sex or marriage than men in order to protect their careers.

'There used to be things women had to do - get married, have children - but 4B is a pushback against these traditions. It is not huge but it exists and we must ask why since it is a significant subgroup of a much bigger social movement,' said author, sociologist and columnist Oh Chan-ho.

South Korea declared its fertility rate a 'demographic national emergency' two years ago and offers handouts for new parents, childcare subsidies, the extension of maternity and paternity leave and urges firms to reduce work pressures. There was delight at a recent small uptick in birth rates.

One legacy, however, is that feminism has become a highly- charged label - with a majority of young men bitterly opposed to the concept since they believe they are the victims of discrimination.

Conservative politicians have won support from young men by campaigning on aggressively anti-feminist platforms, blaming them for the low fertility rate, while young women vote overwhelmingly for more liberal parties.

'Women believe they are way short of where they should be and most men tend to view women as fear-mongering, thinking they are blaming other people for their problems and not viewing reality objectively,' said Oh Chan-ho.

These attitudes soon became evident talking to students in Seoul. 'I would not say I am a feminist to anyone because I might be seen as an extremist,' said Yujin, 21. 'But I know many seniors come up against job issues because firms all want men.'

Several male students, however, accused women of 'playing the victim' and demanding more rights than men. 'They push it too far and want to be above us,' said one. 'Feminists hate men,' said 20-year-old Chan, bluntly.

Some experts argue that debate is dominated by vocal extremists. Others pointed to figures showing a recent rise in the number of marriages, arguing that younger generations may be shifting back to dating and marriage.

But clearly many young South Korean men struggle to adapt to changing gender relations. A study by Joeun Kim, an expert on fertility at KDI School of Public Policy who investigates male victimhood and misogyny, found that 30 per cent believe violence against feminists to be justified - a finding she described as 'astonishing.'

'We have ideological conflict over gender issues, men versus women, and this has depressed fertility because it depressed marriage,' said Professor Kim, adding that 'feminism' had become a derogatory word for many Koreans as a result. 'Misogyny here is not about hating all women. In their view there are good girls and bad girls. The good girls are nice to men and pretty, while bad girls have short hair, no make-up. If you don't look like a woman, you are a bad girl. A feminist.'

Kim - who has carried out a government study into the manosphere in South Korea and abroad - argues that there are lessons to be learnt in Britain, where studies also suggest a backlash against feminism among younger men.

Gender conflict and falling birth rates are not indicators of a healthy society, she insists - so we should take heed of the warning signs from South Korea.

Additional reporting by Andrew Jeong in Seoul