A tough topic to address...
But I answer questions. And if you ask a question genuinely, I will research it. No matter how intimidating it may be.
Polygamy.
So first off, The Church of Jesus Christ of Latter Day Saints does not practice polygamy today. Many people say that the practice ended simply because of political pressure. That is incorrect. Polygamy was never a commandment to the Church. In Biblical times, Abraham, Jacob, and other servants of God righteously practiced polygamy.
It is not a commandment for the Church. It never was. Even in Biblical times.
Abraham had multiple wives, not for sexual gratification or the lust of his own carnal nature. His situation was different. It was not right for all godly men to have multiple wives. It is not the ideal form of marriage. But it was righteous in his situation.
I do not know why God would ever allow a man to have more than one wife. I do not fully understand polygamy. I won't even pretend that I do. But I do trust God. I have faith that He knows more than I could ever know. He knows what each person needs at each moment.
Church members who practiced righteous polygamy in the early days of the Church, were tried. It would be foolish for us to believe that it was easy for them. Imagine it. It would be hard for you if God asked you to. Like many of the things God asks of us, it was hard and foreign. It was a trial. For both the men and the women. But at the time, there was a situation.
Also, the Church teaches (as Christ taught) that we should obey the laws of the land. And thus, we do not practice polygamy.
... Now for what I actually learned most about when studying.
We have to stop looking at things as a "we can, we can't" set of rules. Yes, God has a law. He has principles of righteousness. But all of that is dependent on first and foremost the Gospel. And then the Doctrine.
I compare this to a building. We have a foundation that everything is based upon. It sustains us. This foundation is the Gospel of Jesus Christ. That God loves us so He sent His Son to take our shortcomings, our pains, our weaknesses, our sins upon Him. Then we have the walls. They hold us together. They support us. They support the roof. This is the Doctrine. True and Biblical Doctrine. Then there is the roof. This protects us. It shelters us. It is the Principles, what we see as the rules. For example, we have the principle of modesty. This is not doctrine. This a principle of righteousness.
We focus so much on principles.
Let us return our focus to the Gospel. Let it teach us doctrine. And then let us act on principle.
I do not know why polygamy ever took place. I don't know why it is in the Bible. I don't know why it was in these latter days. But I do know that godly men practiced it righteously in certain situations. And I do know that God has not commanded the Church to practice it. I do know that God has intended for me to be in a monogamous marriage. And I do know that God is the judge.