"Fashion" by Deirdre. A man is introduced to a fashion model by a relatively plain woman. He marries the model but then has an affair with the woman who introduced them. The sex with the plain woman is even more exciting than that with the exotic model.
This is a completely different type of story than I am used to seeing from Deirdre. There is no hint of mind control and the story scores low on the kinkiness scale. It's really a good, interesting story of a romance. An excellent story.