Yeah. A friend who has a PhD in a relevant topic did a great presentation on the phrase "biblical marriage". I forget all the permutations, but aside from the traditional man+wife, there was man+slave, man+wife+slave, man+dead brother's wife, and a few others. Basically, the people talking about biblical marriage were immensely selective in their interpretation of the bible, finding in it the exact prejudices they brought to it.
And the whole argument about tradition, although undoubtedly interesting to some, is irrelevant as far as civil marriage goes. In the recent decision on gay marriage in Michigan, the judge made it clear that "that's how we've always done it" isn't sufficient justification for a law. The state has to have some rational purpose. And multiple courts, including the one that overturned Prop 8, have concluded that the straights-only marriage laws have no rational purpose.
Did you trade some goats for your wife? If not, then gee, I guess we've already made unprecedented changes to a core social institution.