When the Lord explains the Doctrine of polygamy, does He leave any clues as to whether or not He is giving us the whole picture at this time? Let us read D&C 132 :66
"And now, as pertaining to this law, verily, verily, I say unto you, I will reveal more unto you, hereafter; therefore, let this suffice for the present."
Now, just because God didn't reveal everything concerning polygamy,, does not mean that He would go so far as to reveal that this doctrine is a test just like Abraham who received doctrine on sacrificing Isaac,; or would He?
D&C 132 :51 states, "verily I say unto you: a commandment I give unto mine handmaid, Emma Smith, your wife, whom I have given unto you, that she stay herself and partake not of that which I commanded you to offer her for I did it, saith the Lord, to prove you all, as I did Abraham, and that I might require an offering at your hand, by covenant and sacrifice. "
The section also justifies polygamy using the example of Abraham and Hagar, noting that the generations that came through her were" accounted unto him for righteousness. " (D&C 132:37)
Jacob 2:27-30 also defends the rights of women, stating that any man should only have" one wife; and concubines he shall have none; For I the Lord delight in the chastity of woman...For if I will, saith the Lord of hosts raise up seed unto my people; otherwise they shall hearken unto these things. "
Here the Lord recognizes the pain a woman endures if her husband has concubines. He also states the reason for temporary polygamy is to raise children unto Him.
Now we know that even a couple who is sealed in the Temple may not have eternal marriage, for it is written, "If a man marry a wife... and it is not sealed by the Holy Spirit of promise.. then it is not valid." (D&C 132:18).
When we are sealed in the Temple, we may become eternally married as we become sealed by the Holy Spirit.
Abraham was commanded to suffer Hagar to leave him, after her son was born. Thus we are taught that polygamy is not sanctioned by God for the sake of the relationship between the husband and his second wife, only for the sake of the child.
In Eternity, women who are not happy being a second wife or having a husband with multiple wives will have agency to be given to another. This must be in order for God to delight in the eternal chastity of His daughters. This has not been officially revealed, but it can be deciphered.
The sealing doctrine does not take away agency, it allows women to be happily married to a man who is loyal only to them, because if that were not the case, women cannot be sealed by the Holy Spirit of promise if their heart is broken.
The principle of one man per one wife is akin to the brain. One left hemisphere operates through one right hemisphere in order to create. It would be unbalanced any other way.
The Doctrine of polygamy and the Doctrine of a man being sealed to more than one wife is temporary.
In eternity, every man and woman will have the opportunity to enjoy a monogamous relationship.
Joseph was tested much like Adam was tested in Eden. Would he sacrifice his priesthood and prophet hood and even his eternal salvation to be with Emma? When Adam was given the choice of obeying God or pleasing his wife, he chose his wife. Joseph, on the other hand, chose God. This is what God has to say about that. D&C 132:60 states, "Let no one, therefore, set on my servant Joseph for I will justify him for he shall do the sacrifice which I require at his hands for his transgressions,, saith the Lord your God.
God is admitting that by obeying the law of polygamy Joseph was transgressing by hurting his ability to have the Holy Spirit of promise in his marriage to Emma as she would be heartbroken about polygamy. However He was technically doing the right thing, as the Lord says He will justify him.
This puts Emma in a situation. Because Joseph transgresses her heart by obeying God, she is now forced to sacrifice her heart so her husband can obey God. She does not want to do this at all. So Jesus says, "let mine handmaid forgive my servant of his trespasses, and then shall she be forgiven of her trespasses, wherein she has tresspassed against me; and I, the Lord thy God, will... make her heart to rejoice." (D&C 132:56).
Notice how God acknowledges that Emma's unwillingness to completely surrender to polygamy is not a transgression against her husband, only the Lord. Obviously the Lord knows Emma and wants her to do this sacrifice out of her love for Him, not out of a love for Joseph. He knows what a burden this is on her heart, and He promises to make it up to her.
In the Church today, a man may be sealed to a second wife if his first wife is deceased. Reason suggests that this is allowed in order for the man to have companionship, and so the woman can be sealed on earth, giving her the opportunity to be sealed in heaven by the Holy Spirit of promise to the man that she desires.
The scriptures never state that the person you are sealed to must remain your eternal spouse in the next life. They only exclaim that by obeying the new and everlasting covenant you can inherit thrones, kingdoms, principalities, and powers (D&C 132:19). We know from the same section vs 38-39 that David's concubines will be given to another. It is safe to assume the same will happen according to the will, agency, and desires of women in the eternal realms.