Thanks to a friend on Facebook I saw a link to this article about Society, Marriage and God.
"Marriage is part of an earlier notion that women were dependent on men. Women were saying 'if I am going to invest in you by bearing your kids, then you have to commit to me in marriage'. But with women able to earn an equal income, that contract has been weakened."
Not sure how successful a single mum with a kid, after her partner walks out on her or she walks out on him will be at earning high level of income and raising a well rounded child...