Canon Lawyer Pete Vere has an excellent article on the evolution of the Church’s understanding of marriage from both a canon law and theological perspective.
This also reminds me how more states are offering a Covenant Marriage as an option. When a couple opts for the "covenant" marriage, they agree to waive their right to the no-fault divorce. In the event that the marriage does fall apart, only adultery, abuse, abandonment or a lengthy separation will allow a divorce to take place. Strangely they refer to a marriage which can end in a no-fault divorce as a "traditional" marriage.
I would love to be a state employee that issues marriage licenses in these states. I don’t think I would last very long before being fired though. Especially since when a couple asks for a licence for a "traditional" marriage I would have to reply "do you want fries with that?"