I think this is simply what will happen in our secular, post-Christian, relativistic world.
But I think it's absurd. As Strav pointed out, why not legally declare that two horses are "Marriage" or an old lady and her pekingese? If they "love" each other, that's "marriage." How silly.
While there is a tiny embrace of a man and multiple women (polygamy embrace both genders) has some history, for thousands of years in all cultures, "marriage" has been one man and one woman (and generally adult, post-puberty at that). "Marriage" has meaning! And it's not just "love each other." And in most cultures, "marriage" has a religious connotation - it's often understood as a sacred, religious thing. Just just "two or more love each other." Heck, I love my sons and they love me, is that "MARRIAGE?" I love my Dad, is that "MARRIAGE?"
But in this society, GOVERNMENT determines truth. It defines "life" as "wherever the other person is wanted." And "marriage" is just "two people who can vote for me want us to call them married."
But what makes all this... well... weird is that the ONLY advantage to this redefinition of "marriage" as just "they love each other" is psychological. In California anyway (I can't speak for other jurisdictions) ANY group of people can buy a house, adopt children, join their economics, see each other in the hospital, etc. There MAY not be the exact same tax advantages if they are not technically "married" but generally that isn't anything anyway and could be easily changed. So, is there a legal or economic advantage to persons being "married." Nope. And many (including me) are not opposed to "civil unions" where the legal and economic advantages (if any) would be identical to "marriage" but they reject this (passionate) they want to be CALLED "marriage". Pure psychology. "I want to be regarded as "MARRIED" just like my parents." Why? Well.... The price? Throw out thousands of years of marriage, the entire definition of marriage. As Liberals do with many things, tear down things to a level acceptable to everyone.
But this is where our secular, post-religion world is going. I don't think we can stop it. Soon, it will be expanded to include polygamy and we'll find the Cheerleaders at Harvard all being married to each other, union members being one big marriage, a mother and her infant son being married, "marriage" after all just means "love each other." And divorce will soon disappear too, when you fall out of love, you're no longer married. What absurdity - but it's coming (it can't be helped). It would make FAR more sense to leave "MARRIAGE" a matter of family and religion, and for the Government to simply embrace civil unions (or "personal corporations" as they are called in California) - a matter of incorporating under state law. But that would eliminate the psychological thing - the thing they want.
.