According to the Telegraph in the UK
The sharp increase in unmarried couples having children was to blame for the rise in parental separation rates, a study from the Centre for Social Justice think-tank claimed. The report called for a major shift in policy to reassert the “vital” importance of marriage as a more stable form of commitment than cohabitation. The research suggested that the taxpayer spent billions of pounds on benefits for single parents as a result of the “utterly avoidable” breakdown in families every year.
In NZ, it’s $1b each year according to research by NZIER
Growing numbers of couples are choosing to start a family without getting married first. But the study cited figures showing that unmarried couples were more likely to separate. It warned that the number of children who will see their parents split up by the time they are 16 had risen from 40% in the mid-1980s to 48% today. While married couples accounted for over half of all births, divorces represented just one fifth of all breakdowns in parental relationships, with the remaining 80 per cent of separations coming from unmarried families.