It has been seen that monogamy is not always been the expected state for man. Even Christians defend monogamy, as many men in the bible were far from monogamous. Throughout the history of man, most of the societies practiced a range of relationships but mandated monogamy while it is not actually followed.
A research was made on the creatures of nature like insects, animals, mammals etc, and it is found that the monogamy is very uncommon in the natural world. It is also concluded that many species previously lauded as being life long monogamous, are now known to actually have many sexual encounters outside their seemingly monogamous partner.
It is very difficult to find societies which practiced polyandry, where one woman has multiple husbands. We can see in the history that many powerful men have forgone monogamy for the privilege of having multiple female partners. It was not all men who could support multiple wives; only the wealthiest and most powerful men could attract, provide and protect multiple wives and their children.
In United States, monogamy is enforced by law with criminal adultery statues, laws against bigamy and in child custody laws. Infidelity is punishable in many states, while violations of such laws are rarely prosecuted. Monogamy has less meaning that it once did. Even when partners do not sexually violate marriage expectations, divorce rates are as high as 60 percent.
Today, individuals are monogamous as long as they are in a given relationship but once the relationship ends they move on to other relationships, sexual and otherwise. Then why is monogamy the expected and enforced marital ideal? A commitment and bond between two partners meets the need for emotional, social, and physical intimacy, as well as familial, financial and pragmatic needs in ways that no other relationship strategy has as effectively satisfied in the current society.