Why is More than One Wife permitted in Islam?
In the Name of Allah, the Most Gracious, the Most Merciful
Islam is for all societies and for all times to come, therefore, it accommodates various different social requirements. To have more than one wife is neither mandatory nor encouraged, butmerely permitted. The reason for permission to marry more than one is compassion and support toward widows and orphans. Even in such a situation, the permission is far more restricted than the normal practice, which existed at the time of the Prophet, peace be upon him, among the Arabs and other people who married as many as ten or more wives.
Dealing justly with one's wives is an obligation. This applies to housing, food, clothing and kind treatment. If one is not sure of being able to deal justly with more than one, the Qur'an says: “Then (marry) only one." Al-Qur'an 4:3"
There was no restriction on marriages before this commandment. This commandment puts restriction on the number of wives even in exceptional cases. The requirement of justice between the wives ruled out the fantasy that a man can have as many wives as he pleases. God-conscious men do not marry more than one if they are unable to do justice between them. That's why more than one wife is an exception among Muslims and not a general rule. Marriage in Islam is a legal contract and it is not valid unless both contracting parties consent to it. Thus no woman can be forced or "given" to a man who is already married against her will.