Before we discuss this topic, its worthwhile to dwell on an aspect of human relationship between sexes. Do men feel that there is a need for multiple sex partners? Do men naturally desire additional partners for sexual release in a life span ?.
Many research studies have been carried out and it can be confirmed here that man by nature thinks more of sex than a woman. Studies also point out that there is a latent desire by a man for a sexual relationship outside marriage. Men are more likely to be profligate in this matter than women. Why this should happen, cannot be quantified. Perhaps it is because of the physiological and mental make up of the male. Even in animal societies the majority are polygamous and have more than one partner.
In human society there was no marriage when prehistoric man lived, but gradually a need was felt to identify children and set up a family . This was regulated by bringing in the concept of marriage for easy identification of the family. But from history we learn, that man always had more than one partner and this continued for centuries. In Hindu society the concept of more than one sexual partner was accepted as a fact of life. Monogamy was almost unknown in Hindu society for close to 4000 years. The fact that most Hindu men did not practice polygamy was only because of economic constraints. The wealthy and the rich led by the Nawabs and Maharajas never practiced monogamy as they built up a Harem like in Islam, with tens of wives and concubines. The doyen of the Sikhs and a much respected ruler Maharajah Bhupinder Singh of Patiala had 10 official wives and over a 100 concubines( I am not sure of this figure and most likely it was much higher).
The only religion that brought in the concept of a single wife( monogamy) is Christianity. But it is a religion riddled by contradictions and though the Catholic faith does not recognise divorce or polygamy, yet in Catholic nations extramarital sex is most common. A look at society in Italy is an eye opener as almost every second man has a mistress. The novels of that famous novelist Alberto Moravia, bring out this dichotomy of married life in Italy. Moravia has pictured Italian society with all its nuances and extramarital sex with aplomb.
Most psychologists have concluded that man by his very nature tends to be polygamous. Yet man himself brought in the concept of polygamy in marriage. But polygamy has not brought about a suppression of the latent desire of man for another partner. This has resulted in secret liaisons, trysts and extramarital affairs. Another outlet given to a man and a woman is divorce. This is a recognition of the nature of man. society also accepts this desire for another partner in the form of various key clubs where wives are interchanged in a random manner by a game or a lottery. Again , as I have pointed out this is among the well to do and like polygamy being earlier practiced by the rich, such events are again a preserve of people above the economic threshold.
Despite all that I have written, man by his very nature desires variety. He may live with a suppression of this desire for decades, conditioned by religion and mores, but there is no doubt given a degree of latitude most men dream of another partner.
One Religion has recognised this physiological need for another partner and that is Islam. The reasons for polygamy in Islam and its acceptance by the clergy are different, but the net effect is that it caters for a sexual release of a man with another partner in the ambit of marriage. Islam permits upto 4 wives and divorce is much simpler. This does not mean that all Muslim men are polygamous and have more than one wife. Economic reasons will again dominate and in India despite all talk by vested interests the average Muslim has one wife. However the rich do exercise their prerogative and will have more than one wife. This privilege is only for the male and women are excluded.
One can say that in theory a man by being allowed to have 4 wives has an outlet for a relationship with another woman and this is sanctified by canonical law. In a way it is an acceptance of a basic urge of man for sex with another partner.
Polygamy is an outdated concept, but it served a purpose. With advancement in life in all spheres, one can say that polygamy has gone, but the desire of man for another sexual partner has not gone. This goes on and is a facet of everyday life all over the world.
One aspect that needs mention is the de facto presence of polygamy in the CHristian nations. In 1862 the US Congress passed a law banning polygamy. The worst affected was the Mormon Church, which believed in polygamy. Over the decades the men in the west have however got around the law passed by Congress. Men like Donald Trump and Larry king, divorce older women and marry younger woman. They thus extend the fertility period of their lives, something which polygamy would have done. It should also be noted that there is very little reverse traffic and all circumnavigation of the law of monogamy is mostly by men.
Psychologists and research scholars have opined that man is polygamous by nature and this recognition is perhaps only in Islam. But in essence even in other societies ways are available for a man to satisfy his urge for sexual partner other than the woman he has married.
One last fact worth highlighting is that right from historic ancient times men always aspired for multiple wives( albeit a small percentage), but in contrast hardly any woman aspired for polyandry. In real terms most women accepted the restrictions of society in terms of polygamy. The same continues now, except the parameters have changed with quick divorces. In contrast Islam is more forthright in this matter and having multiple partners for sex under the ambit of marriage is a recognition that man is by nature polygamous.