Okay, so, the story is really just one sex scene (or I guess two) with nominal setup, but it feels minimalist and slight even for something like that. The ending is abrupt in the "I came and the sex is over now" sense; I think having anything more conclusive in regards to the characters and their relationship would have done a lot. There's a lot of talk about having dinner, but we don't even get to see it!
Meanwhile, the opening bit at the grocery store is a valiant attempt, but I feel like it goes for the horny register too fast to come off as organic. Moreover, I think that the high-concept premise of the three principal characters being a witch, a vampire, and a weregnoll may be just a bit too much for what the story gets out of it. We spend a decent amount of words on introducing all these things, but only Barry's sudden transformation factors heavily into the sex scene – or his character in general, I guess. Clara being a witch only comes up indirectly; she doesn't even look for her neighbor's lost cat in the Alps... Also, while I understand the choice of protagonist in that this is a "banging a monster" game and not a "being a monster" game, Clara is ultimately sort of a static character – and even though Barry has a vague arc with becoming more open about his condition, it's forced to exist largely as subtext since he's a monster for most of it.
As far as prose goes, let me point to Blue's review, which I think makes many reasonable criticisms. I only want to add that I think the writing is maybe a bit too reliant on adjectives and adverbs; there's a lot of "said gayly"-type stuff adorning the banter that comes off as lack of confidence in the lines themselves.