The Rachel Papers(1989)

Poised to attend Oxford University, 19-year-old Charles Highway decides it's high time to have a romantic encounter with an older woman. With the help of a computer program and several eccentric relatives, Highway sets his sights on seducing Rachel Noyce, a stunning American in her 20s. However, Highway has his work cut out for him. Noyce has a boyfriend, DeForest, and is not exactly receptive to Highway's advances — at first, anyway.