According to both Phillippe and Witherspoon, their real-life relationship made their breakup scene difficult to film. Phillippe said, "I was so actor-y back then and romanticising going through torture to do good work. And I was in love." After two years of dating, Phillippe and Witherspoon actually got married shortly after the release of Cruel Intentions. The two were married for seven years before separating in 2006. Phillippe added that the relationship certainly made filming "more real, or more intense."
In the scene, Annette slaps Sebastian in a gesture that was famously improvised by Witherspoon. (Phillippe has said he even threw up after filming the scene.) "I hit him, and it upset him. We were young, and we just had heightened emotions," Witherspoon said. "But it was great. It was a special time."