A darker side of female sexuality was on display in Cannes on Saturday in a film portraying a woman who seduced a schoolboy and built a picture-perfect life with him after a tabloid scandal.

Starring Julianne Moore and Natalie Portman, "May December" takes the viewer on a rollercoaster of moral ambiguity as it looks at the couple living a life of apparent suburban bliss with their children long after they dominated headlines.

Portman takes the role of Elizabeth, an actor who spends time with the family in order to research a role-playing the woman at the heart of the scandal, Gracie, played by Julianne Moore, 62.

Portman — whose character also takes questionable decisions — told AFP in an interview Saturday that she loved to see the women "behave in morally ambiguous ways."

"The entire range of human behavior should be accessible to women because women are simply humans," she said.

"It always drives me crazy when people are like, oh, if only women rule the world, it would be a kinder place. No, women are humans and come in all different complexities."

Portman shot to stardom at age 12 in "Leon," a film by French director Luc Besson which led her to be sexualized as a child, and towards which she has said she now has complicated feelings.

The film was inspired by Besson's relationship with French actress and director Maiwenn, who he married at 16. Maiwenn starred in and directed "Jeanne du Barry", alongside Johnny Depp, which caused a scandal as it opened Cannes this year.

Besson, who directed "The Fifth Element," has faced several allegations of sexual misconduct, a revelation Portman said she had found "devastating," without wanting to give more details.

"May December" is among several films at Cannes this year taking a deeper dive into the inner lives of women, exploration of their sexuality, or their moral complexities.

"I think that there is no limit to how much it can be explored, so I'd like to see more," said Portman.

The film is directed by American Todd Haynes, who wowed Cannes in 2015 with lesbian drama "Carol," starring Cate Blanchett and Rooney Mara.

He told AFP "May December" explored our refusal to look at ourselves honestly.

"It's how we survive. I believe that we repress a lot of our desires for the best reasons. It's how a civilized society exists by holding back."

Despite the tabloid scandal, and being on the sex offenders list for her sexual relationship with a 13-year-old, Gracie seems incapable of seeing anything wrong as she bakes cakes for her neighbors and prepares for her children's graduation.

However, the arrival of the actor (Portman) and her probing questions strain the fairytale life the couple has built.

Haynes described "May December" as "a very visceral piece of cinema" that reminds him of older movies that had an easier time "asking questions and debating the morality."

He said it was getting "harder and harder to make those kinds of films" with society no longer "comfortable with being uncomfortable. I think that's like the death of thinking, the death of social critique and criticism".