Many marriages in Islam are 'Mubah'. Meaning, polygamy is allowed, but not encouraged.

Scientific reasons: Generally females and males are born in equal proportions. However, due to the high incidence of female infertility, relatively few women are more likely to survive. Apart from warfare, male death rates are higher than women. Accidents and diseases, men's death rates are high. It is acknowledged that women stay longer than men alive. For these reasons, at any particular time, the survey shows that the number of widows is more than the widows. However, in our sub-continent there are more men than women. Because, the newborn baby is destroyed as soon as a woman child. Thus, millions of embryos are destroyed every year in this sub-continent. If this wickedness is stopped then women in our subcontinent will be more in number. According to statistics, the number of women is more than 7800000 men in the United States, 4000000 in the UK, more than 5000000 in Germany, more than 90,00000 in Russia, and more than 78 million people in the United States. In New York only 10 million more women than men. One-third of the population in New York is women. There are 25 million male gay in the United States (not interested in women's marriage). So, if a man marries a woman, then only 30 million women will remain united in the United States. Likewise, in the United Kingdom, 40 million people, more than 50 million in Germany and more than 90 million women in Russia are unaccompanied. Suppose my sister is unmarried in the United States or suppose your sister is unmarried in the United States. Then, there are two ways in front of him. 1. A married man has to accept as a partner. 2. 'People have to be public property. There are many men in the West who are involved in relationships with multiple women without marriage. Then those women are called protectors. It is true that most women expect husband to be his own. But it is better to give up this small expectation in greater interest. Surely no woman would want to see her sister as a protector. Islam has allowed men to marry more than enough to ensure full status of women. There are also other reasons why many men have been allowed to marry in Islam, but for the purpose of protecting the honor and dignity of the women, the main purpose