As a precursor to any explanation on this issue, we must first have a very clear understanding of the concept of marriage in Islam and most people in the world and find out why this question has arisen.
According to the Quran: "It is He [God] who created you from a single soul, and made from it its mate, that he might find comfort with her" (7:189)
Obviously, there are other requirements for a person to fulfill when they decide to get married but Quran names comfort before anything else; that is most probably because the fulfillment of all the other needs also leads to the ease of mind and inner peace.
More interestingly, however, it is not only the holy Quran that says getting married is for the purpose of comfort; having a quick search on the internet makes you realize how all people around the world marry mostly for this emotional purpose, as well:
“…there is an important but neglected positive aspect that explains why people voluntarily enter into commitments like marriage: it is a way of expressing your love and devotion to another person. Not the only way, of course, but a well-established and particularly declarative way…” .
To fulfill this emotional need of a person, the only acceptable form of marriage which is agreed upon by almost all psychologists, and is also recommended by Islam is monogamy. It is within the monogamous type of marriage that all the equal rights of men and women are preserved.
The feelings of love, commitment, loyalty, security, trust, honor, and respect as well as many other benefits  can be fully achieved when one has only one spouse.
The reason has been explained in a comprehensive article. Based on what is discussed there, nowhere in the Quran, you can find a verse that suggests or encourages polygamy among men to attain more pleasure or to satisfy their carnal desires; there are no positive or negative comments on this regular unlimited tradition of the Arab culture.
Instead, the holy Quran imposes restrictions upon it and introduces it as a remedy to a social problem, i.e., the excess number of women in need of marriage over marriageable men, like at the time of war, etc.
Having discussed the concept of marriage in Islam and the limited law of polygamy which is introduced as an exception in case of special social needs, and nothing against the equality of men and women, do you still find the above question unanswered?
If yes, here are some reasons why polyandry is forbidden for women:
It destroys the family which is the foundation of a healthy society. It is usually NOT easy for a woman to perform her duties as a wife and a mother despite having several husbands.
It is against the nature of women and also inconsistent with men's innate desire for exclusivity and love for his wife and children .
It adversely affects women’s health, since women with multiple husbands are more prone to STDs.
It increases sterility among women which will result in population problems.
It may cause identification problems for the conceived child.
It may cause identification problems for the conceived child, which will ultimately lead to legal troubles.
These reasons may clearly show why polyandry is uncommon and frowned upon among Muslims and most people in the world. The Islamic point of view on this issue, however, can be summarized as: “Allah desires ease for you, and He does not desire hardship for you” (2:185), and Allah knows best what is good for you.
Marriage is the tradition of Prophet Muhammad (PBUH) and a sacred union in Islam . Islamic culture tries very hard to safeguard the family and its stability. In the first place, it tells us that we should be very careful when we want to choose our mate. It also gives us a clue as to what characteristics and traits we should be looking for in a spouse .
Secondly, Islamic culture teaches us that an atmosphere of love, cooperation, and forgiveness should reign over every Muslim family, so much so as the Prophet of Islam said, “The best of you are the best-tempered ones with their family.”  Tolerance and compromise is the one vital element of any lasting relationship.
But, no matter what, it doesn’t always keep that way; there are cases in which both sides lose their sense of compromise. One may argue that divorce is not considered lawful according to many Christian views. Nevertheless, its practice by many Christians today shows its irresistibility!
In such cases, the only way to avoid a split is to refer to authority. There should be one person in every group who holds the authority over the group when a dangerous confusion and conflict shows up. But that one person had better keep silent, compromise, and go along with others’ decisions in other than those rare occasions!
In the first step, the husband is that authority in the family, maybe because he is the one who has to provide for the family.
"… The wives have rights similar to the obligations upon them, in accordance with honorable norms; and men have a degree above them, and Allah is all-mighty and all-wise." (Quran, 2:228)
Of course, there is not a tiny difference between man and woman in Islam in the eyes of God; no matter what the gender, the more pious has a higher degree before Him. But as they form a group, an authority is irresistible. Just as we say that there is no difference whatsoever between the president of a country and a simple worker in the eyes of God. Still, the worker should submit to that authority to prevent confusion!
The very verse suggests that it’s not like, men have more rights in the family while women got more duties and responsibilities. No, a wife has as many rights as she has obligations. It also suggests that the husband must treat his wife honorably and respectfully.
If things get worse and this approach doesn't work anymore, we should move on to the next step; that is, a higher authority!
"If you fear a split between the two of them, then appoint an arbiter from his relatives and an arbiter from her relatives. If they desire reconcilement, Allah shall reconcile them. Indeed Allah is all-knowing, all-aware." (Quran, 4:35)
This is actually a very tender council since the two elders are closely related to the spouses and try their best to come up with the best possible solutions for them. The couple, too, are willing to conform to their decision. Going to a marriage guidance counselor is an updated version of or an alternative to this council!
The council might conclude that a divorce is the only possible way for the couple to solve their problem. Sometimes, it’s simply impossible for the couple to go on!
Yes, Islam allows divorce and remarriage, but, as Prophet Muhammad (PBUH&HP) said:
“There is nothing loved by God more than a construction built in Islam by marriage, and there is nothing loathed by God more than a house which is destructed in Islam by separation.” 
It is also narrated that:
“A divorce shakes the throne [of God],”  and “God has not allowed for anything loathed by Him more than divorce!” 
If we think badly of divorce in Islam, it will become our last gasp. But if we do not have a negative outlook on it, separation would be the first thing that comes to the mind at the time of difficulty; “Why should I take all this when I can easily get rid of it?!”
But a mature and broad view suggests that the fruits of that relationship are worth bearing those unpleasant events. Separation is, therefore, inevitably lawful and at the same time very much abhorred in Islamic teachings:
"Consort with them [your wives] in an honorable manner; and should you dislike them, maybe you dislike something while Allah invests it with an abundant good." (Quran, 4:19)
Now, when it comes to separation and divorce in Islam, each side might think that “I got nothing to do with her or him anymore, and so, I can get my revenge on them!”
Of course, many Muslim scholars hold that every woman can state in her marriage contract that she, too, has the right to get a divorce, either generally or under certain circumstances. But, since Islam has basically put the husband in charge of divorce, the Quran commands men over and over that they should honor women, especially when it comes to divorce; if the union is not possible, you must at least have an honorable separation!
These commandments are even in some cases followed by divine threats for those who ignore them:
"When you divorce women and they complete their term [of waiting], then either retain them honorably or release them honorably,…" (Quran, 2:231)
"For the divorced women, there shall be a provision, in accordance with honorable norms—an obligation on the Godwary." (Quran, 2:241)
"If you desire to take a wife in place of another, and you have given one of them a quintal [of gold], do not take anything away from it. Would you take it by way of calumny and flagrant sin?!" (Quran, 4:20)
"… and should they be pregnant, maintain them until they deliver. Then, if they suckle [the baby] for you, give them their wages and consult together honorably." (Quran, 65:6)
And finally, God comforts both sides by saying that, if a divorce is the only way for them and going on with their marriage is much more harmful to both sides than profitable, they shouldn’t worry about its financial consequences:
"But if they separate, Allah will suffice each of them out of His bounty, and Allah is all-bounteous, all-wise." (Quran, 4:130)
The Chapter of “Divorce” in the Quran is also full of merciful verses, which are meant to soothe both parties which are hurt by the inevitable separation.
- Wasa’il al-Shi’a, vol. 20, p. 15, Ihya’ ‘Ulum al-Din, vol. 2, p. 22
- Wasa’il al-Shi’a, vol. 20, p. 49, 50, Ihya’ ‘Ulum al-Din, vol. 2, p. 37,38
- Wasa’il al-Shi’a, vol. 20, p. 171, Ihya’ ‘Ulum al-Din, vol. 2. p, 47
- Wasa’il al-Shi’a, vol. 20, p. 16
- Makarim al-Akhlaq, p. 197
- Al-Kafi, vol. 11, p. 464, Sunan Abi Dawud, vol. 2, p. 254
As stated in the first part, Islam brought about reforms in the customs previous nations, including Arabs, had in practicing polygamy in Islam:
The first reform Islam enforced was the restriction it imposed upon polygamy. Before the advent of Islam, there was no limit to the number of wives. One man could keep hundreds of wives and thus establish a harem for them, just as the ones some kings had, which is strictly banned in the religion of Islam.
However, Islam put a maximum limit on their number, and an individual was not allowed to have more than four wives simultaneously.
The other reform that was made upon polygamy in Islam was the condition under which there must never be, for any reason, discrimination between the wives or their children. The Holy Quran explicitly commands:
"But if you fear that you may not treat them fairly, then [marry only] one" (4:3)
As a matter of fact, those men who can observe full justice with a number of wives are very few. It is clearly stated in the following verse of the Quran which is in association with the previous verse:
"you will not be able to be fair between wives, even if you are eager to do so..." (4:129)
Allah explains here that justice between the wives in its true sense - to stand exactly in the middle of the extremes - is beyond human power even if one may wish it. What a man is obliged to do is that he should not be totally inclined to one of them, leaving the other one as she were in suspense… .
Besides these two main restrictions, there are other responsibilities and duties polygamous men have to fulfill toward all their wives; such as Nafaqah (alimony) and Mahrieh (marriage portion), etc. [see the article about the rights of the wife over her husband]
Ultimately, there is no dispute about the fact that monogamy is better; it is actually the best and most natural form of marriage in Islam. Obviously, the spirit of marital life which is oneness and unity is attained better and with more perfection with a single spouse.
It is only within this form of marriage that family commitment makes sense, and the great bond that unites the hearts of husband and wife makes them become one soul and one flesh .
Polygamy in Islam, on the other hand, rises from a social problem that rests heavily on the shoulders of all men and married women and for which a better solution has not yet been found. We have to face the fact that monogamy is not practical in specific social circumstances, and polygamy -under the mentioned conditions- is the most significant saving factor for monogamy.
One of two alternatives should be chosen: either the restricted acceptance of polygamy -as a duty rather than pleasure-, or the love affairs system, which is common in some societies these days. In other words, a few married men should marry more than one wife -of course under the condition of fulfilling all the above-mentioned responsibilities of a husband in a polygamous family-, and these will certainly not exceed a few percents, and unmarried women should settle, get home and make a life for themselves; or else open the way for love affairs.
In the case of the second alternative, the women deprived of family life may associate at her own free will with several men, and, as a result, almost all married men will in practice be polygamists.
Even then the matter will not end. The wives who will find their husbands to be unfaithful will think of taking revenge upon them and thus will themselves become unfaithful. This final result has been summarized in the well-known Kinsey report in one sentence: “The men and women of America have surpassed all other nations in unfaithfulness” .
Now, which alternative do you think is better?
- Morteza Motahari, women and her rights in Islam, p. 148
- Morteza Motahari, women and her rights in Islam, p. 150
- polygamy in islam