Richard Lyman Bushman writes that Joseph and Emma Hale Smith were sealed on May 28, 1843.
Richard Lyman Bushman, Joseph Smith: Rough Stone Rolling (New York, NY: Alfred A. Knopf, 2005), 494
Emma's concurrence brought about a reconciliation, which led in turn to her and Joseph's priesthood marriage. Joseph probably would not have had the sealing performed while Emma opposed the plural-marriage revelation. But on a cold Sunday evening, May 28, 1843, in the upper room of Joseph's redbrick store, Joseph and Emma were "sealed" for eternity by the power of the priesthood.