(covers information from several alternate timelines)
The two met on Gilgo Beach in 2354 and were married soon after. Later that year, Jennifer and Benjamin attended the Mazurka Festival on New Berlin with Cal and Gretchen Hudson. (DS9: "Emissary", "The Maquis, Part I")
Jennifer and Jake accompanied Ben on his assignment to the USS Saratoga, where she was killed when that ship was destroyed by the Borg at the Battle of Wolf 359 in 2367. Jennifer's death devastated Ben and it was years before he began to move on emotionally. In fact, his bitterness and anger over her death, specifically toward Captain Jean-Luc Picard, whom the Borg assimilated and forced to lead their invasion of Earth as Locutus, almost led him to resign his Starfleet commission, before he accepted that he was trying to escape his memories of Jennifer's death rather than Starfleet itself. (DS9: "Emissary", "The Way of the Warrior")
Jennifer's death haunted Ben for years. He had trouble sleeping around the fourth anniversary of her death. Shortly after, he met Fenna, who he told Jadzia Dax was the first person he'd "felt really drawn to" since Jennifer's death. (DS9: "Second Sight")
Jennifer Sisko was played by actress Felecia M. Bell.
In Voyages of Imagination, Robert Simpson notes that he and Marco Palmieri pitched a story to the Star Trek: Deep Space Nine writers that featured the return of Jennifer Sisko. Their idea was to have it revealed Jennifer was taken from the Saratoga by the Borg and assimilated. Benjamin Sisko would then encounter her. The pitch never sold, although Simpson later used the idea in the Mission Gamma novel "Lesser Evil" for the wife of DS9's new XO Elias Vaughn.