Gavin Rossdale cheated on Gwen Stefani with their nanny? London, ON, Canada / (CFPL FM) FM96 London Jim Kelly November 12, 2015 06:07 am So we all know Gwen and Gavin broke up. But do we know why? There is a lot of speculation that Gavin cheated on her with their nanny. [PHOTO] A while ago, Gavin was caught with his hands a little too close to his nanny’s goods while on a hike with his kids. At least Gwen seems to be doing alright as she dates country bumpkin Blake Shelton.