Reese Witherspoon and Ryan Phillippe
Characters: Annette Hargrove and Sebastian Valmont
Movie: Cruel Intentions (1999)
In the first (and in our eyes, only) Cruel Intentions, Reese Witherspoon and Ryan Phillippe play complete opposites. His character is the asshole who fools around with his stepsister and hers is the sanctimonious virgin who has promised to wait for the right man. You already know how that promise ends up.
For a generation, thier turbulent romance in the movie was idealized by teenage girls (and boys) who wanted to marry Phillippe and to be Witherspoon. The couple met two years before filming the movie, when Witherspoon was 21 and Phillippe was 23. They married two years later and had two children. Their relationship ended after seven years of marriage, when Witherspoon filed for divorce.