Romance as a literary genre is only slightly easier to define than science fiction or fantasy. To paraphrase Wikipedia, the genre focuses on the relationship and romantic love between characters, with an "emotionally satisfying and optimistic ending." Though most popular in English-speaking countries, romance is gaining in popularity around the world as more and more titles are translated into other languages. The genre has also splintered into a dozen or more subgenres (depending on where you draw the lines). Someone looking for happily-ever-after can find it in an urban fantasy setting, or the far future, or the recent past, or via time travel, or with witches and angels thrown into the mix. Romance has also evolved from its original heterosexual, monogamous (usually Caucasian) character set to feature same-sex protagonists, menage a trois, aliens with unusual body parts, shapeshifters, cyborgs -- well, you name it.
Unfortunately, a solid Pagan subgenre has yet to develop. Sure, there are lots and lots and lots of romance novels and novellas and short stories out there which feature magical protagonists. Just type "paranormal romance" into Amazon or B&N and you'll see what I mean. Just because a book features a witch or a lightning bolt-wielding God, however, does not make it Pagan- or polytheist-friendly. I have read far, far too many romance novels in which the Wiccan main character could not recite the Wheel of the Year, the magic was ridiculously flashy and over the top, the Gods were gigantic jokes, and the theoilogy nonexistent. Too often, references to "The Goddess" or "The Gods" are just throw away lines with no real spirituality or faith behind them.
Fortunately, while an official Pagan subgenre may not have developed yet, there are a few romance novels out there which will please a polytheist audience.* Or, at least, they pleased this polytheist audience. So, in alphabetical order: