Perhaps the most difficult aspect of the film is its lack of psychology. We know very little about the Sullivan family except that they "come from a bad place" in New Jersey and that his sister Sissy (Carey Mulligan) has a history of cutting. The siblings express their pain in opposite ways: Brandon internally, and Sissy externally. We don't know how or why Brandon became addicted to sex, but we see that his obsession forms a callus, separating Brandon from potentially painful emotions. In a society where men are rewarded for conquest, Brandon hides his sexual activities from others because they express pain, not pleasure.
Sissy, alternatively, seeks others' approval to fill her emotional void. She moves into Brandon's apartment, hoping the close quarters will beget friendship. Her arms carry scars from years of self-inflicted injury, scars which she chooses not to hide. She also sleeps with her brother's boss in Brandon's own bed, an obvious cry for attention. They are both emotionally lost and flailing, but while Brandon is trying to feel nothing, Sissy desperately wants to feel something, anything.
The NC-17 rating truly betrays the honest, important nature of the film. Yes, we all know that Michael Fassbender is naked, and the MPAA hates full-frontal male nudity. But the amount of actual sexual depiction on the screen is fairly limited and not very graphic (save a three-way tryst). Perhaps the most threatening aspect of Brandon's addiction is that he takes absolutely no joy in his sexual exploits and, indeed, his life. Had Fassbender portrayed Brandon as being more sympathetic, more hopeful, then maybe the MPAA would have given the film a softer rating. However, this would have betrayed the nature of the film -- addictions are very real, very painful, and so very rarely discussed. Fassbender's incredible performance may not create a particularly likeable protagonist, but it creates an important and necessary one. Unfortunately, the MPAA's rating severely neuters the availability of the film, and that's a damn shame. This film will make you come out of the theater craving a cold shower and lots of alone time, but it's a necessary reminder presented in a beautifully constructed melancholy package.