London - More than half of break-ups among couples with children involve unmarried men and women, a study showed.
While there are nearly four times as many families with children headed by married couples, the number of break-ups among cohabitee parents is now higher, according to the Marriage Foundation think-tank.
It said 51.4 percent of couples with children who parted last year were cohabitees and 48.1 percent were married.
Analysing figures from the UK Office for National Statistics, it found a further 0.5 percent were same-sex couples, thought to be divided almost equally between cohabitees and those who are married or civil partners.
It is estimated that in 2006, 45.3 percent of family breakdowns were among cohabiting couples and 54.5 percent among married parents. Family break-ups among unmarried couples living together are thought to have outnumbered those among married men and women for the first time in 2015.
Harry Benson, research director of the Marriage Foundation, said: "The barely acknowledged epidemic of family breakdown continues unabated, caused by the trend away from marriage.
"These new figures show yet again how the odds are stacked against couples who don’t marry. Cohabiting parents account for one in five couples with children, yet more than one in two break-ups.
"If we want to improve family stability – with all the advantages that stability brings for adults, children and society as a whole – we need to rediscover the importance of commitment and marriage."
Benson added: "Our politicians are strangely ambivalent about marriage, yet 89 percent of our current Cabinet are married. For the sake of the next generation, I hope their new year resolution can be to preach what they practice."
Advocates of greater state support for marriage have long argued that married couples are more likely to stay together than those who cohabit.
Cohabitatees who do not marry are estimated to be around three-and-a-half times more likely to break up than married couples.
A marriage that ends in divorce typically lasts more than ten years, compared with three for a cohabitating couple who break up.