I don't mean necessarily about the stealing the son's girlfriend theme, but just about the guy being obsessed with a woman he can't be with.
Paul Avery: Someone should write a *beep* book, that's for sure.
Woody Allen's Matchpoint comes to mind. Also Fatal Attraction, Vanilla Sky, Unfaithful (roles reversed - she's obsessed), A Place in the Sun (Montgomery Clift).
shareTry 'In the Cut'.
It's not about obsession, but writers Josephine Hart and Susanna Moore have similar spare, beautiful prose styles and sensibilities about male/female relationships. Although directed by different directors, the films of both capture their respective writer's stories and style.