In Wing Commander II: Vengeance of the Kilrathi, Spirit was transferred to the TCS Concordia, and one of the few pilots that survived from the loss of the TCS Tiger's Claw. However, a traitor (later determined to be Zachary Colson) reveals to Spirit that her missing fiancé, Philip, was not dead as she feared but was actually on board a Kilrathi space station. She was contacted by the Kilrathi with this information and was tempted to defect, but refused. Later she kamikazed her sabotaged Saber Heavy Fighter into the Kilrathi-controlled Heaven's Gate station holding Philip, killing herself and destroying the station. Her last words to Blair were "Tengoku de omachi shite imasu" (I will wait for you in Heaven).
Source: Wikipedia, "List of Wing Commander characters", available under the CC-BY-SA License.