These films contain excessive graphic violence, intense or explicit sex, depraved, abhorrent behavior, explicit drug abuse, strong language, explicit nudity, or any other elements which, at present, most parents would consider too strong and therefore off-limits for viewing by their children and teens. NC-17 does not necessarily mean obscene or pornographic in the oft-accepted or legal meaning of those words.
One of the earliest of the hardcore marriage education documentaries is one of the more compelling ones in its simplicity. Its impossible to say at this late date whether the couple was truly married or not, but they have good chemistry throughout the film both in bed and their daily lives. The viewer really does come to care about them as people.