Another Nanny! How Gwen Stefani's Fears Gavin Rossdale Cheated With The Help Sparked Their Divorce

Just days after Ben Affleck's nanny scandal exploded, RadarOnline.com can reveal that a babysitter is behind Gwen Stefani and Gavin Rossdale's split too! According to insiders, Stefani's suspicions that Rossdale cheated with the help torpedoed their 13-year marriage.

"Gwen is absolutely devastated about the marriage ending, and she has been inconsolable," an insider told RadarOnline.com. "But she had no other choice. She was very suspicious that Gavin was involved with the nanny."

"Gavin always denied anything inappropriate," the source continued, "but her friends warned her that it seemed like there was something going on."

SEE THE PHOTOS: Gwen Stefani's Bikini Body

In 2012, photos of Rossdale apparently grabbing the butt of the children's caretaker sparked uproar, until it was revealed it was really his sister, Soraya. The couple has since hired new help, but the insider said Stefani has since fired the woman over her suspicions.

"She had no choice but to fire the nanny, and she no longer works for them," the insider said. "Gwen's main concern is simply protecting the kids," Kingston, 9, Zuma, 6, and Apollo, 17 months.

"Gavin was the love of Gwen's life and she gave it everything she could and really did everything possible to save the marriage," the source continued, claiming, "Gavin just didn't seem to be putting as much into it as she did."

SEE THE PHOTOS: Gwen Stefani And Gavin Rossdale Hit The Slopes

As RadarOnline.com reported, Stefani filed Monday afternoon in Los Angeles, citing irreconcilable differences and requesting joint legal and physical custody.

A rep for Rossdale did not immediately respond to RadarOnline.com's request for comment.