Monogamy........In our society it is known as both a secular and spiritual way of life, and in marriage, a law, but what do you think? If you've read the Old Testament, most of the founding partiarchs were openly polygameous and still found favor and were loved by God. So, why did this idea start?
Here is one theory...........
Christianity was propagated from the Roman Empire into the West and from the West into the rest of the modern world. And wherever the gospel is preached, Roman monogamy was portrayed as God’s only divine standard. But because the major part of the world is still unchristianized, there are actually much more societies of the world that are polygamous than monogamous. "Should-be" monogamy never gained worldwide attention until the last few centuries. The should-be monogamy idea was not popular in previous generations, not until its strong uprising in the last 150 years or so. In fact, polygamy was still openly practiced in the last generation in non-western countries, and is today still practiced in modern societies, even though not so openly because of the outcry it would cause. A worldwide ethnographic survey of 849 human societies show 708 whose customs are polygynous (more than 1 wife), 4 polyandrous (more than 1 husband) and 137 monogamous. Other than the religious and supremacy factors, there can be a few other reasons for this.
In real modern day practice, monogamy is but the exaltation of free love and the justification of self-love. Possessiveness is not only condoned, but glorified. That’s why it is so appealing. It readily satisfies the inner desire of a woman to possess her man exclusively, and the inner need of a man to please and idolize his woman completely above all other things, to be completely engrossed in her only. Dr Nathaniel Branden, an advocate and authority on the subject of romantic love, has well defined it in his book, Taking Responsibility, "Romantic love means finding a soul mate – someone whose values and sense of life mirror our own. We feel a drive to organize our life around this person and no one else. If someone says, ‘I love you’ in a romantic context, this what they are understood to be saying."
Control.....Some say that the concept of monogamous marriage ultimately stems from men's attempts to keep track of the lineage of offspring in early historic times. Given the nature of sexual reproduction, women always know which children are theirs, so as long as a family's name and wealth are passed through the female line (matrilineal descent) there is no problem. But if men want to pass the family name and inheritance through the male line (patrilineal descent) then things get messy. Even prior to the rise of civilization and the concept of inheritable wealth, one can detect obvious biological pressures to keep female sexual behavior committed to a single male, but once civilization takes hold and great sums of wealth are on the line, the biological pressures are supplemented by very powerful social and political pressures. What this ultimately means is that, for the purposes of biology and patrilineal decent, men don't have to be monogamous, but women do. If that was the reason, then with the advent of DNA Paternity testing, would this still apply?
On the other hand......Most women would benefit from polygyny, while most men benefit from monogamy. HOW!?! You Say...........When there is resource inequality among men—the case in every human society—most women benefit from polygyny: women can share a wealthy man. Under monogamy, they are stuck with marrying a poorer man. The only exceptions are extremely desirable women. Under monogamy, they can monopolize the wealthiest men; under polygyny, they must share the men with other, less desirable women. However, the situation is exactly opposite for men. Monogamy guarantees that every man can find a wife. True, less desirable men can marry only less desirable women, but that's much better than not marrying anyone at all. Men in monogamous societies imagine they would be better off under polygyny. What they don't realize is that, for most men who are not extremely desirable, polygyny means no wife at all, or, if they are lucky, a wife who is much less desirable than one they could get under monogamy.
Whatever your feelings on monogamy, it is the way of life now. By the standards of our modern sensibilities, monogamy may have been an improvement over what appears to have been millions of years of polygany(the practice of one man having two or more wives, which is often confused with the term polygamy, which means have more than one spouse).