Mid 1843 - Joseph Smith (Age: 37) married Olive Frost (Age: 27), who was at the time married to Parley P. Pratt.
"In October 1839, twenty-three year old Olive Frost was living in Dixfield, Maine pursing her interest as a “tailoress”. In a later biography Olive’s sister, Mary Ann, wrote, “Elder Duncan McArthur visited that place and preached the Gospel as taught by the Latter-day Saints, in such plainness that her willing mind, already prepared by earnest prayer, soon comprehended its vast importance, and she received it joyfully.”" (In Sacred Loneliness: The Plural Wives of Joseph Smith pg 588)
"Mary Ann had joined the church three years earlier and moved to Kirtland, Ohio. There she met and married Apostle Parley P. Pratt. In the spring of 1840, Mary Ann, Parley and their three children left for England on a mission. They stopped in Maine and persuaded Olive to go with them. Mary Ann wrote, “[Olive] willingly forsook father and mother, brothers and sisters, and braved the dangers of the great deep, to aid in spreading the Gospel in a foreign land. These two sisters were the first missionary women of this dispensation to cross the sea going and coming. Sister Olive was not afflicted with seasickness, and was therefore enabled to devote herself to her sick sister and care of the family”" (In Sacred Loneliness: The Plural Wives of Joseph Smith pg 589)
"Their mission complete, Olive and the Pratts arrived in Nauvoo in April 1843. There, Olive lived with some old friends from Maine, Patty and David Sessions. She also socialized with Eliza R. Snow. Both Patty and Eliza had become wives of Joseph Smith a year earlier and Olive, herself, was soon introduced to plural marriage. Mary Ann remembers, “She seemed to realize and appreciate the magnitude of the great and important mission allotted to woman in the perfect plan of this Gospel dispensation, and she desired to do her part in the good work. She freely accorded to man the title of king, and joyfully accepted the place of queen by his side. It was at this time that the principle of plurality of wives was taught to her. She never opposed it, and, as in the case of baptism, soon accepted it to be her creed, in practice as well as in theory. She was married for time and all eternity to Joseph Smith...”" (In Sacred Loneliness: The Plural Wives of Joseph Smith pgs 589–590)
"About the same time as her marriage to Joseph, Olive joined and participated in the Relief Society women’s organization. Said Mary Ann, “She was very zealous in soliciting aid for and in visiting those who were needy and in distress. Her heart was always tender towards suffering of every kind, and it gave her unbounded joy and satisfaction to be able to relieve it.”" (In Sacred Loneliness: The Plural Wives of Joseph Smith pg 591)
"After a year of marriage, Olive lost her husband, when Joseph Smith was killed in Carthage. The writings of Nauvoo resident, Ettie Smith, indicate the strong attachment Olive must have had for Joseph, “When the dead bodies arrived at Nauvoo, the spiritual wives of the late prophet, before unknown with certainty, now disclosed by cries, and a general uproar, their secret acceptance of the new doctrine. One of them, Olive Frost, went entirely mad...”" (In Sacred Loneliness: The Plural Wives of Joseph Smith pg 591)
"Olive lived in Nauvoo for another year, until she became ill and died on October 6, 1845." (In Sacred Loneliness: The Plural Wives of Joseph Smith pg 592)
Source Material: http://wivesofjosephsmith.org/31-OliveFrost.htm