Who owns “Marriage”

Who owns the term “marriage?” Is “marriage” a term that belongs to the Church, society independent of the Church, or both?
I have heard it said many times that most gay people are not that concerned with getting “married,” per say, meaning that all the ceremonial trappings and many of the ideas of heterosexual marriage are not a necessity for the survival of their relationships. After all, successful gay couples have had to survive without State and Church approval, and in most cases within hostile environments. Whether the Church gives its blessing or the State gives them a license does not make their relationship any more valid in their own experience. Considering that nearly half of all heterosexual marriages do not survive, including born-again Christian marriages, State and Church sanction will not make that much difference in the good survival of their relationships, it seems. Yet, for purposes of equal treatment under the law, at least State sanction can be an important aspect of gay relationships – survivor benefits, rights of visitation, taxes, equal treatment in housing, work, et cetera.
Is the word “marriage” the domain of the Church? This means the Church needs a well-developed theology of marriage, which it lacks. (Who controls marriage – is a couple married when they receive the piece of paper from the State, or when they finish the ceremony within a Church? Perhaps neither, but when intercourse first takes place? Does the Church want to relinquish control to the State?) The problem is that the Church and Christians have been such miserable failures concerning marriage survival rates.
What about Civil-Unions? The way the State deals with the issue gay couples and the way the Church deals with the issue should be very different. When the Church demands that the State accept its definitions and reasoning that result in the denial of equal protection for one segment of the population, then we have problems with the establishment of religion…