Helen, Psyche, beauty—"To Helen" is chock full of references to love, mostly of the, ahem, mythical kind. All these references to mythological love, while they sound cool, are a bit depressing. They aren't real! In other words, the poem describes a love that is ideal, that is more of a fantasy than a reality (remember that Poe had his friend's mom in mind, after all). This doesn't mean it can't be awesome and beautiful and fun to think about, though. Right?
Love can be a dangerous business! The names Helen and Psyche remind us of powerful love affairs but also of war, violence, and suffering.
Sometimes, love is just too perfect to be real. All the mythological references in this poem imply that love is a myth—an ideal or fantasy.