Juan Rico / Fame Flynet 1 / 10
Juan Rico / Fame Flynet 1 / 10

Little is really known about what went wrong between Charlize Theron and Sean Penn, but it seems that the actress felt a little disconnected -- or rather, she made Sean feel that way.

"Charlize wasn't responding to his calls and texts," a source told Us Weekly of the stars' split. "She just cut it off."

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The "Mad Max: Fury Road" star's feelings seemed to have changed rather abruptly, too. The now-former couple was the picture of happiness during the Cannes Film Festival in France last month. But then, she just stopped.

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"Sean and Charlize looked very happy together while at the Hotel Du Cap," a second onlooker told Us, "with no signs of tension or a breakup."

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Shortly after the split was reported, it was the said Charlize was the one who pulled the plug on the relationship of a year and a half.

The once-engaged stars are reportedly not speaking to each other.