Emma married Joseph in January 1827, when they were both in their early twenties. Emma was slightly older than Joseph and better educated. Emma's father strenuously objected to Joseph, and the couple had to elope to marry.
Emma was supportive of Joseph in every way, even when her father's 1830 ultimatum forced her to choose between the family of her birth and the man she'd married. Joseph received the revelation on polygamy in February 1831, mere months after Emma left her parents behind forever.
It is unclear whether Emma was supportive of polygamy at any time or how much she knew about Joseph's activities.
The traditional assumption is that Joseph went behind Emma's back, but this isn't the only hypothesis that fits the data. It is plausible Emma could have been completely aware of Joseph's belief he'd been commanded to practice and teach polygamy. This knowledgeable Emma would have been in a position to forbid Joseph from acting on God's command to marry other wives, or forbid conjugal relations between Joseph and other wives.
Joseph's first probable plural wife was Fanny Alger. The earliest possible date of Fanny's marriage to Joseph was a full two years after the 1831 revelation, and Fanny did not bear children until years after her time in the Smith household. These two points - the two year delay and Fanny's childless state - are not consistent with a Joseph who merely wished to sate his carnal lusts.
Emma treated Fanny like a member of the family - it was said Emma loved Fanny like a daughter. In late 1835 Emma allegedly caught Fanny and Joseph together in the barn. Around this time Joseph dismissed his boarders, including at least one single man nearly Joseph's age. The common assumption is Joseph and Fanny were in the midst of intimacies and Emma had been unaware of any marital link between the two. But consider if Emma knew Fanny was Joseph's wife and had demanded they refrain from becoming intimate. Not so bad for Joseph--he had Emma. But that would leave Fanny without the possibility of intimacy or children. Further, she had no rationale for refusing suitors who were unaware of her ceremonial marriage to Joseph. What if one of the boarders had been courting Fanny? Might not Fanny be justified in confronting Joseph about what being his wife actually entailed?
Following the confrontation in the barn, Fanny left the Smith household and the community. Joseph gave up his efforts to teach plural marriage, and censured others who aspired to enter into plural marriages at that time.
Five years later Emma was present at her father-in-law's deathbed and witnessed Joseph's blessing at the hand of his dying father. Father Smith blessed Joseph that he would "not die until all that has been ordained shall be accomplished."
Joseph wept, demanding "Will I? Will I?" Later that fall, Joseph reportedly resumed his attempts to practice and teach plural marriage, which he referred to as the "New and Everlasting Covenant." Marriage in the New and Everlasting Covenant sealed a man and woman together such that death would not part them (though wickedness could). Being sealed in the New and Everlasting Covenant didn't necessarily imply mortal marriage, though it almost always did after Joseph's death.
Emma rejected Joseph's teachings about the New and Everlasting Covenant until May 1843. It is unknown how much Emma knew about Joseph's 'marriages' to the wives he accrued between 1840 and May 1843. Nor is it clear if any of these women "knew" Joseph in the biblical sense. There is every reason to believe Emma knew about each of Joseph's 'marriages' after May 1843, and several incidents suggest she felt it was her right to control these later marriages.
- Emma requested Joseph marry Eliza and Emily Partridge in May 1843 in conjunction with her own acceptance of the New and Everlasting Covenant. Almost as soon as the Partridges were her husband's wives, Emma did everything in her power to prevent any opportunity for intimacy. Three months after forbidding any intimacies between Joseph and the girls, long enough to ensure neither girl could possibly be pregnant, Emma demanded the girls leave her household and the city. Though Joseph refused to send the girls completely away from the city, he agreed to the girls' banishment from the household.
- Joseph's final plural marriage was to Fanny Young, in the fall of 1843. Fanny was a widow twenty years Joseph's senior and sister of his eventual successor, Brigham Young. By all accounts the marriage was on a whim, arising from Fanny's assertion she'd be happy to be a ministering angel in heaven. Emma became furious when she learned Joseph had sealed himself to Fanny. There is no hint the relationship between Joseph and Fanny Young was intimate, nor is there any hint Joseph tried to conceal the fact of the ceremony from Emma. It seems, then, the source of Emma's rage was that she had not been consulted about whether she wanted Fanny Young as one of her husband's eternal wives prior to the ceremony.
- In the winter of 1843/1844, Jane Manning became a member of the Smith household. Jane was valiant, attractive, and black. When Jane could not find work elsewhere in the city, the Smith's hired her to be the cook in the hotel-like Mansion House. Jane says Emma proposed Jane be sealed to Joseph... as a daughter. Jane was unwilling to supplant her own beloved parents, even if the 'adoptive parents' were Joseph and Emma. Jane fled the Smith household, only later understanding the implications of Emma's offer. It is fascinating to contemplate whether Jane would have accepted Joseph as a husband rather than as a father.
Joseph Smith was killed in June 1844. Brigham Young required Joseph's wives to re-solemnize their marriages to Joseph in the temple when it was completed in December 1845. However the man standing in as proxy for Joseph (or proxy for any other man, for that matter) would be married to the dead man's widow until death (or divorce) parted them [a policy abandoned after 1846]. Emma was unwilling to marry any of the men who could have served as Joseph's proxy in the temple. Emma refused to follow Brigham Young west, preferring to stay in the city where Joseph had lived and where his body and debts remained.
Emma remarried and lived in Joseph's abandoned city for the last decades of her life.