There is a perfect mate out there for everyone. At least that's the basic premise of romance--except for ménages. In those cases, there's more than one perfect person, but they're all perfect for each other.
In the current market, the perfect mate might be a werewolf, a vampire, an animal shifter, or even a gargoyle. And the other half of the equation could be almost anything--even a human. A friend recently wrote a story where one of the characters is part of a tree, not a new concept, but different than the normal run of characters.
So what is the attraction? Why are we so fascinated by the notion of non-humans and multiple partners? Could it be that we live with the less than ideal, deal with the mundane and long to fulfill that long ago little girl dream that our prince indeed will come to rescue us?
While we're waiting, that romance about two handsome men who focus all their talents on pleasing one woman gives us something to daydream about. Or that fabulous dragon shifter will scoop us up and take us away to magical lands.