This poem is in fact about his wife, Virgina, who was also his cousin. Everybody in Poe's life left him, his father and mother abandoned him. Then his mother died, he was adopted and as an adult became astranged from his adopted parents. Then when he married the love of his life, she, too, died. Poe suffered from depression all of his life. Its obvious in his actions, not just his writings.
He wrote this poem in 1849. It would be one of his last. In 1850, Frances S. Osgood, a close friend of Poe's, identified Poe's wife, Virginia, as the real Annabel Lee. Virginia died in 1847, completely destroying Poe's well being. The rest of his life was spent in a deep depression that he tried to dull with liquor and drugs until his untimely death.
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