Assalam-o-Alaikum wa Rehmatullah wa Barakatuhu, brother as far as I have been with scholars and studied the Qur'an and Sunnah I have not come across any such particular 'reason' for going into Polygamy. And Allah has said:

> "then marry those that please you of [other] women, two or three or four. But if you fear that you will not be just, then [marry only] one or those your right hand possesses. That is more suitable that you may not incline [to injustice]." [4:3]

You may like any girl, whilst you are married, and so you can marry her too. Or that you like to support someone, so you may marry her. Or there can be any reason for marrying, from most stupid to most intellectual. Islam has allowed a Men to have at max 4 wives at one time, and there are no prerequisites attached to it. But **BE SURE TO PROVIDE THEM THEIR DUE RIGHTS, ELSE NOBODY WOULD EVER BE ABLE TO SAVE YOU FROM ALLAH'S PUNISHMENT....**

May Allah's peace be upon All.