The strict pattern for marriage is to protect and honor the chastity of women, in which God delights. Whoredoms have always been an abomination in the sight of God. Unless this and other commandments were kept by the Nephites, God said the land would be cursed for their sakes. The only exception which the Lord makes to the rule of monogamy is when it is his will to raise up seed to the Lord. In that case he will specifically command the people to do so. In the absence of any such revelation, the people are bound to the rule of monogamy as set forth above.
Even when multiple marriages have been mandated by the Lord to raise up seed unto him, such marriages are under very strict rules laid down by the Lord. First of all, no plural marriage is allowed unless the Lord has authorized it. Secondly, no man can enter into a plural marriage unless his first wife has approved it. This is called the law of Sarah, who is Abraham's wife.6