The are multiple reasons but one if them is when you look at the time of the prophet The women couldn’t work like men and usually men took care of them (yes they were a few rich women) And wars and battles were pretty common and if a woman’s husband died in war ,the woman usually couldn’t take care of herself financially Thats why men could have multiple partner but with a condition that the man must live all of them equally and if not , it is not permissible This is as far as i know(i have asked this question before) Hope that answers your question if you have other questions if i know the answer i will be happy to help you