Several tabloids printed photos of McGregor kissing actress Mary Elizabeth Winstead at a cafe in West London. The two were seen having a romantic meal then speeding off on a motorcycle together.
Many were shocked and thought McGregor was cheating on Mavrakis, whom he has four children with. That's when the separation details came out.
McGregor and Winstead met while filming the third season of the FX anthology series Fargo.
Winstead also split from her significant other, husband Riley Stearns, back in May.
McGregor and Mavrakis married in 1995 after meeting during filming an episode of Kavanagh QC.
Photo Credit: CTMG / Jaap Buitendijk