This is one of the better structured movies ever put to screen. It's as complex as Lynch's Lost Highway, but that only adds to the experience. A non-linear structure (in time and space) is applied and Lucia y el Sexo blurs the line between reality and imagination.
Basically, it's like Mulholland Drive: Most of what we see is a dream, imagination. Only a relatively small part did really happen. But this goes one step further: What part is in the eye of the beholder here, because little clues are given so the mystery format is only used to keep us entertained at a basic level.
A writer is the center here. Some parts of his life are probably true (trouble at home, sickness), others are ambiguous, others are certainly imagined. He is in the meta-story, but also places himself in threads in the other stories that come from his imagination. His imagination is formed by applying smaller and larger events (meeting a person at a party, seeing someone in front of the house) in his personal life to his fantasies. His erotic fantasies explain the title, as sex is one of the characters of the story. One of the story lines is again about his script read on the island by one of his imagined characters. Writing the story and telling the story is done simultaneously. As he becomes sick, the characters become helpless in the story. Overall it helps a lot if you keep imagining that you're watching imagined characters being manipulated by the writer. This combines meta-story and story, real with imagination, weaving several threads in a complicated web of story lines. In the end, it is made clear that the story doesn't end but starts again halfway, giving further evidence that viewers can use their imagination at random on this and create their own story out of it.
The meta-story is interesting, but by mixing it with the story itself we see the real story as what it is, a writing trick with imagined characters. That unfortunately diminishes the emotions a movie tries to convey. We're merely watching how a movie is structured, with the imagined story not having the usual dramatic impact.
It's remarkable that so many people are offended by the sex scenes, as it's already in the title. Do they also complain about the presence of aliens in Alien? I found the sex scenes to be made with some honesty; and at least they didn't even shy away of male nudity.
