What is Poe suggesting about the impact of losing a loved one in "Annabel Lee"?

Edgar Allan Poe wrote this poem as he was witnessing the slow death (from tuberculosis) of his young wife, Virginia Clemm Poe.  He imagines all too clearly the separation her death will bring to their love.
In the poem, Annabel Lee has already died and left the speaker bereft.  He declares that neither angels in Heaven nor demons in Hell can ever separate their eternally entwined souls.
The memories of Annabel Lee are permanent for him, and there will always be reminders of her in the natural world.  When the moon appears, he gets lost in dreams of her, and when the stars come out at night, he imagines her bright eyes.
In the final stanza, the speaker describes lying next to her burial chamber, unable to move on with this life.  Clearly, the impact of losing a loved one can drive a survivor to irrational and obsessed behavior, according to Poe's speaker.
https://www.poetryfoundation.org/poems/44885/annabel-lee