What Marilyn Monroe was to men, Valentino was to women. He represented the ideal demon lover, who would carry the woman away into a romantic ecstasy where she could create fantasies about the Sheik. Of course, being carried away by the demon lover into a romantic us-two-aloneness goes on in modern films as well. Generally if women are unhappy in their relationships with their husbands or their lovers, they dream and fantasize about being carried away and having a secret, nocturnal love affair with their animus.
I've just finished up the fourth season of the Dr. Who reboot (the David Tennant Doctor) and, well, first off, that was one of the most emotionally draining and moving things I've ever seen. While this doctor is one of the most engaging, he's also one of the most wounded, and his pain revolves around being essentially ageless in a world where everyone he ever gets close to, everyone he ever loves, will die (if they don't leave him first.) Now, who does that sounds like? Hmmm... VAMPIRES! And gods.
Humans can't marry gods. In We: Understanding the Psychology of Romantic Love, Robert Johnson interprets Tristan's turning away from the flesh and blood woman he married ("Iseult of the White Hands") for the unearthly princess of the "foreign land" (i.e. his anima), also named Iseult. The gods - the archetypes - belong out of time, while we humans must live in time. To lose touch with the life giving archetypes is to live a half life, a life without life or meaning. But to live wholly in the other world is just as destructive - we see that fate in the lives of those who, like Tristan, reject the flesh and blood loves of this world for the pure, unearthly loves of the archetypal world.
Characters like Edward and the Doctor are essentially gods. Other characters can become gods (the way Bella is turned into a vampire) or gods can become human (as happens in Dr. Who... but I'm not giving any more away!) but the two can't mix. How much of that happens when, dissatisfied with the real Iseult (or the real Tristan for us women) we mortal humans give all of our love and passion to an undead and undying creature?