Charlize Theron reportedly broke up with Sean Penn by not answering his calls. Here, Penn and Theron arrive for the screening of the film "Mad Max: Fury Road" at the 68th Cannes Film Festival in Cannes, southern France on May 14, 2015. Reuters

“Mad Max” actress Charlize Theron reportedly broke up with boyfriend Sean Penn during the Cannes Film Festival in May by simply refusing to take his calls. The couple, together only 1 1/2 years, are allegedly no longer a couple, even though Penn just directed “The Last Face” with the actress.

"Charlize wasn't responding to his calls and texts," a source told Us Weekly on Friday. "She just cut it off."

The couple began dating in December 2013 and were secretly engaged in December 2014, according to Us. Theron confirmed the two were together in several interviews last year.

“Look, we’re dating, and I don’t think we were trying to hide anything. We were photographed; the relationship was kind of written about … What I will say is I was single for a really long time,” Theron told Vogue in June 2014. She said the two had been friends for 18 years and that she “really didn’t see it coming.”

The 39-year-old also told Esquire in April that she considered herself lucky to have found Penn. The South Africa-born star has dated actors Stuart Townsend and "Third Eye Blind" lead singer Stephen Jenkins in the past.

“I’m a very, very, very lucky girl. Very lucky. He’s hot. He is hot. How do you say that in an interview? You’re a 40-year-old woman sounding like a 16-year-old,” she said to the magazine, as reported by USA Today. “There’s something beautiful about that, but you lack the articulation of really saying what it’s like when somebody walks into your life and makes you see something that you really never thought you’d be able to see.”

Though the couple reportedly called it quits, an additional source said there was no sign of trouble while the two attended the Cannes Film Festival together May 13-24. "Sean and Charlize looked very happy together while at the Hotel du Cap," an onlooker confirmed to Us, "with no signs of tension or a breakup."