Ыex is so huge and so amorphous. It's everything. It's not just pornography. It's not just cheating on a spouse. It can take so many forms.
As a writer, I think your first job is to find a subject that you think you and others will find inherently interesting.
What I learned was there are hormones, and most people are sexual. They may go through stages where they might do things where they go above and beyond, but this is something else.
Just write what you love and what a movie you'd like to see.
