what is the theme for anabel lee?

The work returns to Poe's frequent fixation with the Romantic image of a beautiful woman who has died too suddenly in the flush of youth. As indicated more thoroughly in his short story "The Oval Portrait," Poe often associated death with the freezing and capturing of beauty, and many of his heroines reach the pinnacle of loveliness on their deathbed, as with Ligeia of the eponymous story.

Annabel Lee is the love of the narrator of the poem; the love that is described is a very young love which will go on eternally.  The narrator implies that the angels were jealous of this wonderful love and thus took Annabel Lee away from him to heaven.  She is now gone, but the love lives on in the narrator's heart.