I edit a lot of sex scenes. What can I say? A lot of people I work with write romance and/or erotica. While I also get my share of fantasy, sci fi, thrillers, and so on, even they can have a sex scene or two thrown in. And when I say thrown in, I mean they are built into the story so they make sense with the characters, not just thrown in like an HBO series does as the backdrop for a scene about something else entirely because they can.
I read one of the best posts about writing sex scenes, and I highly recommend every writer contemplating adding one read it, too. Chuck Wendig, of Terrible Minds, devoted one of his 25 Things lists to sex scenes. Read it here. Then read it again. Maybe print it out and hang it near your desk. Yes, I admit to being a Wendig fan girl, but once you read his blog, you’ll see why.
Adding sex to your story should enhance it, not make it screech to a stop, have a sex break, then start back up again. If 90% of your story is sex, not only does it have to make sense to the story and BE a part of the story, you have to mix it up. We’re talking about more than flowery prose or a list of body parts. Each scene has its own arc. Each scene is a scene. Oh, just go read Chuck’s post. He’s already said it better, funnier, and with more detail.