Marriage was first a way of regulating inheritance and it then became a means of enforcing the morality of the dominant culture -- in everything from child-rearing to sexual comportment (mandatory monogamy under the adultery laws).
"Family values" is often a coded expression for the nostalgic perpetuation of misogynstic and sex-phobic agendas, including the belief that society will degenerate into chaos if pleasure is not regulated through marriage. Psychology and religion ally themselves in America against unconventional relationships and means of child-rearing though there is utterly no evidence (but plenty of "intuition") that the state's sanction and the classic two-parent, mixed-sex household are necessary to maintaining a cohesive society.
I have worked with several divorcing couples recently and I have been astounded at the way the new "mediation" laws, far from aiding relatively friendly departures, often seem to inflame blame, to pressure people to stay married, etc. I'm unclear whether this is the intent of the law or is inside the culture of judges, lawyers and professional mediators administering the system. I went to one hearing recently and had to repeatedly remind the officials that my clients were divorcing amiably, had agreed upon a property settlement, even if their lawyers didn't, and that they were there to demonstrate that, not to legitimate their wish to divorce.