If your sex scene isn’t integral to the plot, then you’re not doing it right. Maybe you’ve heard that sex is just supposed to happen every fifty or a hundred pages. Wrong. Even if what you’re writing is erotic romance, the moment needs to be right, and something should happen to move the characters along or the scene will fall flat and feel gratuitous. The most important thing about writing a sex scene is remembering that it is, in fact, a scene like any other in your novel. That means that all the same rules apply. When writing sex, you…