Winstead and her ex had no children together while Ewan his ex have four children.
United Kingdom publication The Sun got photos of Ewan and Mary Elizabeth kissing at a cafe in London before leaving on a motorbike.
Married Trainspotting star Ewan, 46, spent more than an hour at the fashionable establishment with Mary Elizabeth who plays his lover in United States telly show Fargo. The couple shares four daughters, including a girl they adopted from Mongolia in 2006.
McGregor and Mavrakis, a production designer, were married in 1995 after meeting on the set of the British TV series "Kavanagh QC".
"The cafe was really busy with people including delivery drivers coming in and out the whole time". They then left together on McGregor's motorbike.
"They were deep in conversation and were there together for more than an hour", the diner said.
Sharing a photo of her kissing her Texan film director ex on the cheek on Instagram in May, the actress wrote in the caption: 'We've chose to move on from our marriage, but we will stay best friends and collaborators for all our days'. We have spent our lives together and it has been full of joy and warmth every day'. "We are still ride or die, just in a different way now", she said on Instagram in a now-deleted post that was captured by People. "I love you always, Riley", Winstead wrote, according to The Cut.