The age difference between Rachel Bernard and Tony D. is 25 years. at the time of filming the scene he was 44 years old and she was only 18.
The director of the film instructed Rachel Bernard to not show a lot of enjoyment during sex because it's supposed to be awkward and weird doing it with an old man who's friend with her parents. in reality, she hated the the sex so much it worked for the movie's plot.
Rachel Bernard hated doing her scene with Tony D. and said that there was nothing sexually arousing about a scene like that.