Rex / Rex USA 1 / 25
Rex / Rex USA 1 / 25

Will the Cannes Film Festival bring back bad memories for Charlize Theron and Sean Penn? Industry insider are reportedly concerned that it might.

Sources tell Page Six "The Last Face," which stars Charlize and was directed by Sean, is likely to snag a screening at Cannes this spring, which would force the pair into a promotional blitz in the locale where they were last seen together as a couple.

After a year and a half-long romance that featured days spent bonding with Charlize's son, Jackson, romantic kisses on Malibu, Calif., beaches and nights out at galas and Oscar parties, the pair suddenly split shortly after the 2015 festival. They were rumored to have been engaged at the time.

And while there was never much in the way of confirmation about what caused them to go their separate ways, Us Weekly reported Charlize had done the dumping by simply cutting off communication without warning.

These days, says a source the Post calls a "showbiz insider," "they hate each other."

The tab's sources point out, however, that Charlize followed through with her reshoot responsibilities on "The Last Face" after breaking up with Sean.

"These are professionals, whether in a romantic relationship or not," says the snitch.

They were also pals long before they started dating.

Speaking to Vogue in 2014, Charlize said she'd known Sean for 18 years prior to their romance.

"We were just really good friends. And it's been slow going because you are aware that you could screw that up and lose it," she explained.

"We had to think about it. But at the end of the day, it was somewhat effortless. It just kind of naturally happened, and before I knew it, I was in something that was making my life better - the people who really love me can see the effect it has had on me."

If Charlize is dating someone new in 2016, the "Mad Max: Fury Road" star has kept it under wraps. She adopted a second child -- her daughter, August -- in August 2015. Since then, she's been busy with multiple projects, including "American Express," which IMDB reports is shooting now.

Her ex, meanwhile, was reportedly spotted sharing "many kisses" with a young blond woman at a steakhouse in Chicago last week. Shortly after breaking up with Charlize, he was rumored to have been seeing Minka Kelly. She later nixed those reports after sharing a meal with Sean, tweeting, "Not dating a friend I had a group dinner with. #sillymedia."

This year's Cannes Film Festival kicks off May 11. Other films expected to be featured there include the Kristen Stewart-centric "Café Society" from Woody Allen and Jeff Nichols' "Loving," which, like his previous films, features Michael Shannon.