"Unwrap Party" by Jordan Shelbourne. Sarah is jealous because Richard is flirting with Crista at the party; and so she takes up with Ben in order to make Richard reciprocally jealous. The author does an excellent job of examining the feelings of Ben and Sarah without being the least bit boring. As the story evolves, it becomes obvious that Sarah's and Ben's affection for each other is genuine and also that Sarah has a major problem with feelings of inadequacy. She is preoccupied with having an orgasm, and these very thoughts interfere with the big bang.
This is an outstanding story. The author has a way of describing extremely hot sex so that the reader can almost feel it happening, and he shows a real understanding of emotions. I am definitely going to watch for more stories by this author.