While the vast majority of films rely on body doubles and camerawork to accomplish the illusion of actual sex acts between characters, there are a handful of movies that skip the smoke and mirrors entirely. These movies all contain real sex scenes between their actors. Some of them are extremely explicit and others more subtle. But all of them are unsimulated.
The 2005 movie Lie With Me, based on the novel by Tamara Berger, follows a man and a woman in Toronto who initiate an intense affair. The sex scenes are extremely graphic and also real.
The film was released to mostly negative reviews. It has a fairly dismal 38% rating on Rotten Tomatoes.