The 55-year-old singer was photographed walking the Pomeranian he used to share with Gwen named Chewy all by himself at a park in Los Angeles on Thursday.
Wearing his favorite cargo pants, Rossdale slipped into a white t-shirt and left his curly hair undone.
Clutching his cell phone in one hand, Stefani's ex-husband looked intense while having a conversation with someone on FaceTime during his afternoon stroll.
At one point, the Bush frontman plopped down on a grassy knoll to stretch out all this tension while letting his tiny dog run free.
Rossdale's solo walk comes on the heels of rumors that he's already having issues with Shelton.
Stefani married the country singer in an intimate ceremony at Shelton's Oklahoma ranch on July 3.
Rossdale -- who shares three sons with Stefani -- and Shelton are reportedly clashing over co-parenting.
The former married couple are parents to Kingston, 15, Zuma, 12, and Apollo, 7.
Rossdale wants to talk to Shelton "man-to-man" and "lay down some ground rules," reports The Sun.
“He’s gotten ticked off at Blake in the past for seemingly overstepping his bounds, and is ready to make it clear he has final authority with the boys," an insider revealed.
He “also wants to make it clear that badmouthing him in front of the kids won’t be tolerated," their source added.
Rossdale wants to make sure the trio are successful at co-parenting so he wants to "say his piece sooner rather than later."
Stefani and Shelton's ceremony was so intimate that they left several people off the guest list.
As Radar reported, the country singer's television bestie Adam Levine wasn't even invited!
We're told the former Voice judge found out about Stefani and Shelton's nuptials like everyone else ... in the media.
“Adam had no idea when Gwen and Blake very going to get married. Adam wasn’t invited to the wedding and was not given the heads up despite the fact that Blake and Adam used to be as close as brothers when they were both onThe Voice together,” sources told Radar.
"This was a wedding for close friends and family. Not Hollywood celebrities,” they added.