As the events of the poem unfold, there are three distinct moods created through the details.
The mood at the beginning of "Annabel Lee" is mystical. The speaker begins with "It was many and many a year ago," which is reminiscent of a fairy tale beginning "Once upon a time, long long ago." The speaker then tells of a "maiden" whose only thought is to love him and be loved by him. It sounds very much like a fairy tale full of loving tales that end "happily ever after," and this feeling flows into the next stanza with descriptions of an unearthly love that is so strong that "winged seraphs" envy the couple.
The third stanza begins a mood shift to one of despair. Suddenly, Annabel Lee is killed by a darkness and the speaker is left alone as her "highborn kinsman" take her away. Thus, Annabel Lee leaves him both spiritually and physically.
Before the poem ends, the mood shifts once again to reflect the eerie attachment that the speaker holds for Annabel Lee, even in death. He feels that their souls are forever bound together and cannot be separated; therefore, he lies by her sepulcher night after night, listening to the same sea that stands by their "kingdom" in the first stanza.
There is no happy ending, and this is no fairy tale. Instead, the couple faces a darkness which causes the death of Annabel Lee and forever changes the speaker into a man forever tortured by dreams of the love he had and lost.