From what I've heard on this topic there's so many variables to this issue that's is amazing. For example in my opinion the length of the marriage doesn't mean squat when it comes to the issue of parenting. What matters is the the man/bf and wife/gf as individuals and their ability to be a cohesive parenting unit. Another that was mentioned is the single mother gaining support from the man, but they're times where the man isn't suitable as support or the mother herself isn't suitable to raise the child/children. Kind of going on a tangent when I say we don't live in traditional times, but there is some value in tradition. What really got me thinking was when Drew said that marriage was the first institution introduced to children and if that doesn't work then it makes it hard for children to believe in other institutions. The thing that came to mind was that parents can also introduce their children to drug abuse and alcoholism. Ugh there's so much to write, but this is just my opinion