Sometimes we ask ourselves if God truly allow polygamy. In the Old Testament, we see that some men like Abraham, Jacob, David, and Solomon had more than one wife. God did not punish them directly for it, which makes it seem like He allowed it at that time. Most of these men had family issues because of polygamy due to jealousy, fighting, and sadness. This shows that having many wives often caused more trouble than peace.
In the New Testament, things became clearer. Jesus talked about God’s plan for marriage from the beginning. He said that a man should leave his parents and be joined to his wife not wives and the two shall become one. Also, when the Bible talks about church leaders, it says they should be “the husband of one wife.” This shows that God wants one man to be married to one woman.
God have found out that polygamy brings about hatred in some families which is not what God wanted.
I totally agree with this. It's best to stick with one partner.