The Realms of Water
Novella 19,733 words Recommended by 2 award/anthology sources
"Three days into their journey, and the strangers—humans and one janusian couple—felt as if they had become respectable friends. A convincing illusion, and essential. The male janusian, rooted firmly into his wife’s broad back, was eager to outline the situation."
Quasar links out; the story lives on Asimov's, where the author gets the click.