The 52-year-old actor and the brunette beauty are said to have had an on-off fling since 2004, and according to new reports, rekindled their affections just last month.
According to Us Weekly, Monika stayed over at George's Los Angeles mansion, and things seem to have heated up between the pair.
"They spent hours talking, and have an incredible connection," an insider told the publication.
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The former flames were spotted flirting at London nightclub Loulou's earlier in May, when the Gravity actor was still going out with his then girlfriend Stacy.
"They danced and held hands," claimed the source. "He's been calling and texting Monika ever since."
Stacy meanwhile, who officially split from the Hollywood star in July, seems to have moved on from her two-year relationship with George.
The television personality recently shared a photo of her drinking wine in a restaurant in Paris, cuddling up to businessman Jared Pobre.
"Stacy and Jared are dating," an insider said. "They met through friends, but they are not anything more than dating."