It's always very difficult and dangerous to generalize about how people think and act. In the area of sex this is particularly so, but a few comments might be useful. First, Parisians like to talk about sex. They love to verbalize fantasies, exhibitionist yearnings, private desires, etc.
Sex is in the air.
The popularity of sex as a subject doesn't necessarily translate into the act. It would be absurd to say, and hard to verify, that the French make love more than any other people, although they like to think they do. In fact, they're more driven by the pleasure of the act of seduction than by the results. The supreme art is the combat verbal. If you find yourself impatient with the relationships in contemporary French films, maybe this explains it.