Despite accounting for just 19 per cent of parents, by the end of 2013 cohabiting couples are set to overtake married couples in experiencing relationship breakdown.
According to the Marriage Foundation, this year is the first time in British history that more unwed couples have split up than those who have tied the knot.
The foundation made the warning in a new report after analysing data released by the Understanding Society last month which suggests that unmarried parents are four times more likely to split up than those who have wed.
Cohabiting couples currently account for 48 per cent of family breakdown cases but the report predicts that, based on present trends, the percentage of family breakdowns in unmarried households will rise to 50 per cent by the end of 2013.
While an average of 5.3 per cent of cohabiting couples with dependent children under sixteen years old split up each year since 2009, only 1.3 per cent of equivalent married couples were found to have broken up in the same time period.
"This marks a significant tipping point for society today," said Harry Benson of the Marriage Foundation. "We hear so often that rising rates of divorce is the cause of growing family instability, but these statistics prove how far that is from being the case."
Divorce rates in the UK have been falling since 2004 and Benson believes it is misguided to suggest low income and poor education are to blame for family breakdown.
"The average income and level of education has improved since the 1980s, while family breakdown has doubled," he said.
"We haven't been getting poorer or less well educated...but we have become less willing to commit to our families.
"The link between declining numbers of marriages and increasing levels of family breakdown is plain for everyone to see."
He argues that family breakdown is having a significant impact on society, saying it has a "detrimental effect on children's wellbeing" as well as costing the tax payer £46 million a year.
In response to the statistics, he has called for greater commitment to marriage, saying "parents and future parents should seriously consider making a concrete commitment to their family by getting married, or at the very least making a clear plan for where they are headed".
The importance of marriage is echoed in the Government's plan to give low-income married couples a tax break of up to £200 a year from 2015.
The tax break was welcomed by the Archbishop of Canterbury, the Most Reverend Justin Welby, who said: "We welcome all support for married life and we're pleased that this initiative includes both married couples and those in civil partnerships."
