Gavin Rossdale Jealous Blake Shelton Spending Time With Gwen Stefani & Kids

Gavin Rossdale may have finally realized what he's lost after seeing Blake Shelton with his ex-wife Gwen Stefani and their three young sons, Kingston, Zuma and Apollo. Although he will forever be the father of the boys, he doesn't have the right to control Stefani's relationship with the country crooner--and that is making him upset.

"[Blake is] a big hit with Gwen’s kids. It drives Gavin nuts that his kids have bonded with Blake," the source told HollywoodLife exclusively. "He hates that they’re spending so much time with him. He doesn’t have any say in it…and it’s killing him.”

The 50-year-old Bush frontman and the No Doubt singer ended their 13 years of marriage after the latter found out that Rossdale cheated on her with the nanny Mindy Mann.

Rumors of Rossdale's infidelity started way back in 2012 after photos were released of him with his hand on Mann's butt while they were on a hike with his two sons. The singer quickly slammed the rumors saying that he was only helping the nanny not to trip and fall.

Even after his denial, Stefani filed for a divorce and she has since moved on with the 39-year-old country superstar. The rockstar found support in Shelton who also went through the same ordeal with his now ex-wife Miranda Lambert.

Shelton and Stefani had no problems flaunting their love for each other. Fortunately for the 46-year-old "Used to Love You" singer, her boyfriend enjoys spending time not only with her but also with her kids.

“Blake is amazing with the kids. He’s such a big kid himself and loves doing all the same things as they do,” another source told HollywoodLife exclusively. “One of his favorite things to do with them is go on hikes — they love Malibu Creek. They get out there in the mud, hunting for frogs or playing hide-and-seek. Blake loves any excuse to get outside and get dirty, so he’s a big hit with Gwen’s kids."