Radiance by Grace Draven

I love it. It's dark, it's cozy, it's sweet, but people are still getting their heads cleaved in twain. Essentially (and without spoilers), the story starts out with our two mains getting arrange married because alliances and whatnot; they are each from a race that thinks the other is quite ugly looking, but otherwise they're fast friends and have each other's hideous backsides when danger hits, and then eventually they each of them think that the others' backside is maybe, possibly, perhaps not so terribly hideous after all. It's good. Enjoy.