Gwen Stefani, Blake Shelton Romance Reportedly a Challenge for Her Ex, Gavin Rossdale

Gwen Stefani has happily moved on from her marriage to Gavin Rossdale, which ended in 2015, by dating Blake Shelton. But while both Stefani and Shelton seem to have seamlessly formed their own family, with Shelton helping raise Rossdale and Stefani's three sons, Kingston, Zuma and Apollo, Rossdale might not be taking their relationship as well.

"It is challenging for Gavin to watch his boys grow closer and more attached to Gwen's boyfriend Blake," an anonymous source reportedly told Hollywood Life. "As Gwen's relationship with Blake continues to grow stronger, Gavin struggles with how much quality time Blake spends with his sons, time that Gavin sometimes feels should be time that he is bonding with his own sons.

"Gavin appreciates that Blake is a great guy and he knows how much the boys enjoy fishing and doing country things with Blake, things that Gavin would not or could not do with them, so Gavin understands," the source continued. "However, Gavin reminds the boys that he will always be their real father because he fears any hurt the boys may endure should Gwen or Blake decide to split one day."

Rossdale's fears of a split between Stefani and Shelton seem unlikely. The couple, who was just spotted attending Easter services at church with her three sons, have been dividing their time between her home in Los Angeles, and his Oklahoma ranch, where Stefani enjoys taking her three sons.

"It's very tribal," she told Marie Claire of her home away from home. "Blake has a sister, she comes with her kids. We cook and get muddy and dirty. There are ATVs. Being a mother of three boys, it's kind of the perfect place. Everything is real now, whereas before, things didn't seem so real."

Stefani and Shelton met when they were both serving as coaches on The Voice, while Stefani was in the middle of her split from Rossdale, and Shelton was ending his marriage to Lambert. In hindsight, Shelton acknowledged that no one likely expected their rebound romance to last.

"When I was going through my divorce, I hit rock bottom, just like anybody does when they go through something that devastating," Shelton said on Sunday TODAY. "It's a miracle that I met somebody that was going through the same exact thing that I was at the exact same moment in time."

"If Gwen and I were being honest right now," he added, "talking about this, I think in the back of our minds we both kind of thought, 'This is a rebound deal because we're both coming out of a pretty low spot in our lives and we're kind of clinging to each other to get through this.'"

Photo Credit: Getty images/Christian Petersen