Winstead allegedly dumped her Fargo co-star because fans were claiming she was a 'marriage wrecker' after McGregor left his wife for her.
When quizzed by reporters about the break-up Mavrakis said: "No, I hadn't heard."
"I really don't know. Sorry."
The 44-year-old French designer - who has daughters Clara, 22, Jamyan, 16, Esther, 15 and Anouk, six, with Ewan - recently admitted the end of her 22 years marriage to the 'Trainspotting' star was "disappointing".
The pair announced their split in October last year after McGregor, 46, was spotted growing close to Winstead, but court documents listed the date of their separation as May 28, 2017.
But now there are reports that Winstead, 33, has dumped the famous Scottish star.
A source revealed: "Mary hated the embarrassment of being labeled a home wrecker.
"Ewan decided to throw his marriage away for Mary, and now it looks like he's lost both."
Both McGregor and Winstead were spotted out together in and around Hollywood while also attending some awards ceremonies too.
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