In an interview with Vanity Fair, the actress - who appears alongside Ryan Gosling in the forthcoming drama - recalled an intimate sex scene that she filmed with the actor which was later cut from the theatrical release.
"I was comfortable with it and it just felt more vulnerable, you know? There's actually a very good reason for it. And the way we shot it went a lot further, but it ended up getting cut," she explained.
"What happens is, I come into the shower with Ryan, and for my character, it's a smart ploy. She just found out that she got accepted to a medical college, and he's afraid he's losing her. He's threatened by everything that's happening to her and he just had this weird moment when he jumps into the water and gets their boat and writes their telephone number on it."
Dunst continued: "What happened in the shower scene, she comes in and we start making out, and I gesture that I'm going to go down on him. And then I do."
All Good Things hits US theatres in limited release on December 3.