(covers information from several alternate timelines)
Sometime in 2370, she attended a Ktarian music festival, where she met Starfleet officer Ensign Harry Kim, who had mistakenly sat in her seat. Three weeks later, Kim plucked up the courage to ask Libby out and the two began a relationship.
Libby, whose last name was not given, was played by Jennifer Gatti in her second of two Star Trek appearances. She only appeared in "Non Sequitur" but the character was further referenced in "Persistence of Vision" and "The Thaw".
In the Voyager novels Homecoming and The Farther Shore, Libby resumes her relationship with Kim, although she has since become an agent for Starfleet Intelligence during his absence. The novels also state she is a musician and gives her last name as "Webber." Libby also appears in Star Trek: Voyager - Spirit Walk novels Old Wounds and Enemy of My Enemy, in which she covertly assists the senior staff when a Changeling impersonates the first officer during a mission to Loran II.
Libby and Kim broke up in 2379 after she rejected his marriage proposal. She later became engaged to Aidan Fletcher, who also worked for Starfleet Intelligence.
The novel Pathways gives Libby's last name as "Lattimore."
According to The Autobiography of Kathryn Janeway, Libby married Kim after his return to the Alpha Quadrant.