There's plenty of sex-related material in The Catcher in the Rye. Yet, there's a lot of foreplay and not any actual sex. Holden just isn't ready to go there, and probably because sex is one of the dividing lines between being a child and an adult.
But while The Catcher in the Rye also deals with the darker side of sex: molestation and abuse. Holden may or may not have been the victim of sexual abuse on several occasions since he was a kid, and it looks like Jane, too, may have been abused by her stepfather. This helps to explain why Holden is so hesitant to have a sexual relationship with anyone.