I don’t think there was any real legitimate reason behind Ligeia other than what it was — a short story. It has been speculated that the story was actually a satirical work of the gothic fiction genre, but I personally don’t agree with this considering “gothic mood” of many of Poe’s works. Assuming you were also the anonymous person who asked in a question if the story was about Virginia, it couldn’t have been. Ligeia was published in September of 1838, and Mrs. Virginia Poe contracted tuberculosis in approximately 1842, nearly 4 years after Ligeia was published. Poe lost many people he loved throughout his short 40 years, and it is no secret that he was fascinated by death. In short, Ligeia was a short story about how even in death, love is a powerful emotion that can’t even be broken in between both the afterlife and the living world.