Romance follows fairy tale structure. Not mythic quest structure. Can't say that often enough. Study Voegler, study Campbell, if you think it will give you something to think about or a point of comparison. But never forget, dear romance author, that you're actually writing a fairy tale.
Say it with me now. Fill in the blanks.
"And they all lived ______ _______ _______."
This concept is so intrinsic to genre romance that authors have shorthanded it: HEA, for Happily Ever After, a/k/a the way the good romance novel ends.
There is some debate about the shape and form of that HEA ending. Vladimir Propp, the Russian formalist who studied thousands of local wonder tales and created a 31-step template for this type of folklore, held that the final step was a wedding. All other steps -- whether obstacles, challenges, triumphs, or meetings -- led inexorably to the wedding IF the protagonist was successful on the journey. Cinderella marries the Prince in the final moments of her story.
Now we're less inclined to view a formal wedding ceremony as essential to the HEA. Now we discuss this ingredient in terms of the promise of commitment or the proof of an enduring relationship. Regardless, the final moments of a romance novel will demonstrate to the reader that the pair-bond has been created and will not break. The form of that pair-bond can vary a little, but its presence is mandatory.
Or, as Leslie Wainger puts it in Writing a Romance Novel for Dummies (which is actually a damned smart book),
The final expectation every reader has when reading a romance novel is that it will end with the hero and heroine expecting to spend their lives together and face any future trials as one.
Compare this to the mythic quest structure, which ends with the hero recrossing a threshold and becoming the master of two worlds. Dorothy returns to Kansas in the end and is as comfortable there as in Oz. But she doesn't marry the wizard, does she? Of course not. Marriage can occur along the path of the hero's journey, but it's not the destination.
I'm going to keep this short -- there's more I could say on this subject, but my goal in this post is to make you think about the differences between fairy tale endings and mythic quest endings. A lot of you are going to resist these ideas because you've been taught quest structure as if there are no other options. There are. And we use them. We just don't always recognize them.