This has been driving me crazy for the past few days. I remember reading a short story a few years ago where the (if I recall correctly) the central plot twist was that this guy go together with a woman who turned out to be shapeshifter, spending her nights as a cat. Unfortunately, I can remember that many details. I believe the guy at some point commented that this woman's breath was always fishy, or something like that. At first, I thought the story was written by Neil Gaiman, but I've been looking through the various short story collections of his that I have, and I just can't find the story. Sorry I can't be more specific, as I don't remember many details about the story. If anyone has an idea which story this could be, I would be eternally grateful for any clue. Thanks so much in advance!