Excellent, excellent point.
If we roll back to even the most advanced forms of civilization that history has brought forth, nothing of what they had to offer is even barely comparable with Holy Matrimony.
And indeed we found all sorts of unions. It is also the merit of the Church if many of those unions are now considered to be not just morally wrong, but even against the law of the land.
From the standpoint of reason alone, we may want to re-read what the philosopher Thomas Aquinas had to write on the topic. It is very clear from the standpoint of reason - meaning, not from the standpoint of faith - that Holy Matrimony as presented by orthodox apostolic Christian faith is the highest fulfillment of the natural union between male and female, and that all other sorts of unions that can be loosely termed “marriage” fall way short of this, and ultimately contribute only to making the people and the society more miserable.
Don’t say no, just look at the facts and figures first, learn about the history. There’s so much nonsense talk nowadays about women’s right, but nobody really recalls who was the promoter of women’s rights in the age of concubinage and prostitution. Nobody remembers who said: “there is neither man nor woman, neither free man nor slave, but all are one in Christ”, who is God - therefore making everyone of equal dignity, and that dignity being that of children of God. Nobody remembers who defended the dignity of virgins, who defended the values of modesty and chastity, who defended the dignity of the wife, of the mother, of the widow. This is because there is a keen ignorance of the history of our world. We only learn the basics, but the important details are overlooked. Oftentimes, a partial image is presented by those historians that have an agenda under their coat. Study the situation of women and how Christianity changed it. Learn about the great women saints of the Chuch, some of which are even honored as Doctors of the Church and studied all over the world by thousands of people. Learn about how the Church honored at once the figure of woman, virgin, mother, and spouse in Our Lady, Mary mother of Jesus. Learn how ever since two thousand years ago the Church reminded husbands to love their wives just as Christ loves the Church, His bride.
This nonsense that we are experiencing is the slow-moving collapse of the values of society. As God is removed from the picture, so are all values. But when we remove God from the picture, as a wise man once said, “we do not worship nothing: we worship anything”. Or, rather, we become our own gods. Or we delude ourselves that way, at least. Pride, vanity, and lust - spotted as the three great problems of the human being since two thousand years ago - become the new values of society. Their fruits: relativism and hedonism. To them, the Church has opposed and still opposes poverty, chastity, and obedience. Poverty in spirit, which is not found in absence of money but in absence of attachment to worldly riches. Chastity, which is not the suppression of our sexuality but the achievement of true balance and self-mastery in a truly fulfilling way. Obedience, which is not blindly following without understanding, but listening carefully to others and humbly following that which leads us to forget ourselves and focus on helping those who are more in need than us, trusting that others shall do the same for us. This is the meaning of living in a community.