The practice or custom of having more than one wife or husband at the same time. – Wikipedia “Polygamy”
Polygamy was practiced in the Old Testament by both wicked and righteous people.
Because God pronounced the greatest blessings that God can give, (Eternal Life or Calling and Election Made Sure), on many people who were not living polygamy, it is clear that living polygamy is not required for these blessings.
Likewise, God has blessed a number of people with these same blessings, (Eternal Life or Calling and Election Made Sure), while they were living polygamy, (including having sex and offspring with their multiple wives), therefore we can be certain that living polygamy does not damn a person and prevent them from obtaining these most precious blessings.
Joseph Smith wondered what the Lord’s take on Polygamy was and how it was that several of the righteous in the Old Testament lived polygamy and were blessed for it. He inquired of the Lord and received the revelation known as Doctrine and Covenants Section 132.
D&C 132:1
1 Verily, thus saith the Lord unto you my servant Joseph, that inasmuch as you have inquired of my hand to know and understand wherein I, the Lord, justified my servants Abraham, Isaac, and Jacob, as also Moses, David and Solomon, my servants, as touching the principle and doctrine of their having many and
This revelation was not published until after Joseph Smith’s death. Before it was published, Brigham Young made certain changes to the revelation which contradict verses within the revelation as well as other verses in scripture making the revelation’s authenticity suspect. (See Elliaison commentary on D&C 132 for more detail.)
In the revelation, the Lord tells Joesph that a man or woman can marry whomever they want, be it one person or multiple people, but the revelation also says that unless the Lord ratifies the marriage by sealing it with the Holy Spirit of Promise, it will have an end when men are dead.
As with all things, marriage is a personal choice and should not be dictated by others, (who you marry or whether you marry one person or many people). Regardless of your choices, your marriage relationship will end unless the Lord ratifies it with the Holy Spirit of Promise. All relationships ratified by the Holy Spirit of Promise will extend after this life. (See Holy Spirit of Promise)