As an historian, this strikes me as words of wisdom :
You can't even change the future, in the sense that you can only change the present one moment at a time, stubbornly, until the future unwinds itself into the stories of our lives.
-- Larry Wall in perlmonks
In The Knight, The Lady, and the Priest, Georges Duby, historian and medievist, analyses the transformations of occidental society between the Xth and the XIIth centuries, with some focus on the marriage institution.
During this period of time, a new feudal system was progressively put in place and a new balance of power was found in the occidental kingdoms. As a consequence, the patrilineal transmission of domains and titles began to become the rule; to sustain this societal change, it was necessary to make the marriage more rigid, notably by disallowing the common practice of divorces, marriages by rapt, and repudiations.
And that's where the Church intervenes. Previously, the Christian religion didn't care much about marriage. Jesus didn't -- he declared that in the kingdom of God, there will be no husbands or wives; actually he didn't care much about family values in general (see Luke 14:26 for example). Paul, the co-founder of Christianism, wasn't very concerned either: it's better to be married than to burn, did he wrote, but it was clear that the true Christian was to be celibate in his mind.
So the Church started to introduce during the XIth century mandatory marriage blessings, and then, a couple generations later, full-fledged ceremonies. Pope Gregory VII forbid the marriage or even concubinage of priests. Marriages that were not approved by a priest were declared invalid. Nobles, even kings, were excommunicated when they didn't follow the new rules. Progressively it became a sacrament.
There was some resistance to the new institutions; as usual in those Christian times, they took the form of heresy, although the heretics, this time, weren't the reformers, but the traditionalists.
This new form of marriage has stuck until us. But remember: when someone talks about sanctity of marriage, he's actually speaking about an opportunist theological innovation invented by some French and Italian bishops during the eleventh century for purely political reasons.
