I found the Spousonomics interview with Betsey Stevenson and Justin Wolfers exceptionally intelligent and entertaining, and you might enjoy it as well. They begin with a discussion of why they chose not to marry, which I imagine will prove controversial in some circles:
Because Betsey and I earn similar incomes, we would pay a marriage penalty. The U.S. has a household-based taxation system which subsidizes married families when one person stays home and taxes most people extra if they choose to marry and both work full-time. The average tax cost of marriage for a dual-income couple is $1,500 annually. When our accountant ran the numbers for us a few years back we discovered marriage would cost us substantially more. I love Betsey and all, but is the marriage certificate worth thousands of dollars annually? I can love her plenty without the certificate. But this isn’t just about a bean-counter saving his beans. Truth is, I find it offensive that the tax man treats me differently according to a very private decision—whether I marry or not. And so I prefer to remain unmarried, at least in the eyes of the tax man. And I would also be more sympathetic to the formal legal institution of marriage if it were open to all couples, not just straight couples.
Stevenson adds a different dimension:
It’s not all taxes and politics. It’s also contracts. Marriage is a contract between two people about how to organize their lives together. But modern marriage is a one-size-fits-all contract—a default written by the state legislatures. It makes no sense to me that I would want to sign the same contract with Justin that you sign with your partner. So we didn’t take the standard off-the-shelf contract that we call marriage. Instead, we’ve talked at length about what is important to each of us, and it’s that Betsey-and-Justin-specific agreement that guides our lives together. And as anyone who has studied divorce knows, the formal marriage contract doesn’t actually bind our future selves. But I have something far more enduring with Justin than a wedding certificate: We have an amazing daughter, who will bind us together for, well, until death do us part.
As Stevenson would acknowledge, different couples would make a different calculation. For many American couples, children don’t prove enough to bind a nonmarital couple together. In Scandinavia, in contrast, nonmarital unions tend to last longer than in the U.S., particularly when children are involved. Some people place higher value on the totemic affirmation of which Stevenson and Wolfers are notably skeptical.