Note, please, that despite splinter groups to the contrary, successful civilizations generally accepted that one man with one woman was the normal familial arrangement, even in the absence of Judeo-Christian teachings.
Ever wonder why that was?
Because it is the most stable framework for raising children, the one which has few conflicting interests besides raising the children in the family of two parents, which provides the stability necessary to care for and pass the culture on to those progeny.
Multiple wives create conflict over which children will receive most heavily of resources available to the family, something which happens even today in 'Brady Bunch' style families (the TV show, not the anti-gun advocates).
Despite all our supposed 'maturity', there is a definite and instinctive tendency to protect and nurture our own progeny ahead of others in the immediate environment, which can be overcome to provide an egalitarian environment in which all children are loved and nurtured the same, but often is not.
So, as social 'concepts' go, the most viable, after centuries of testing has proven to be the traditional one man one woman marriage. Those tend to be better formed if the union is not taken lightly as in the case of readily available divorce, and longevity provides the structure by which a society, a culture, and its traditions can propagate and continue into the future.
Otherwise, the tendency is for disruption of a culture (as we are seeing in America today), with the crumbling of the nuclear and extended family. Once the traditions, the values, and the essence of that culture is no longer passed along in that context, each successive generation can be set against another, and the culture crumbles--easy fodder for those who would seize control of the rudderless and lost populace.
Whether one chooses to believe the religious material in the Bible, at the very least there is sound advice for a stable and civil culture to be found there.
And so you concede my point. All else is irrelevant.