The reality TV star is supposed to spend an equal amount of time with each of his wives separately, but Radar reports that when the cameras are not rolling its clear that he spends more time with Robyn than he does with Meri, Janelle, or Christine.
"It appears Kody's official home base is wife Robyn's house," a source exclusively told Radar. "He didn't go to another wife's home for almost a week."
The insider also noted that Brown drives a white Infinity SUV, a blue Lexus sports car and a motorcycle, all of which were parked at Robyn's home for a week, recently.
His third wife, Christine, was reportedly out of town with her two oldest daughters, but the source says "when she returned on Saturday, May 11, he did not visit her."
"It seems Robyn is his true wife," the source said, adding that Janelle also did not get a visit from Brown. "The rest are just living their own lives!"
Notably, Roby is Brown's only legal wife, as he divorced original wife Meri so that he could take Robyn as his bride and legally adopt her children from a previous marriage.
While the source says that Robyn seems to be getting all Brown's attention lately, he previously confessed that he and Meri have been "dating" and working on their relationship.
"We are dating," he said on the show's recent season reunion. "We literally got to a place, it just got nasty. And like no, we're not gonna do that anymore ... I am cutting off everything that was the past. It's a new date, it's a new girlfriend, it's a new person, but we have a history and we also know each other."
However, Radar notes that Meri went multiple months without posting any pictures of Brown, and that she has even been somewhat flirtatious with men she met on a cruise ship.
Brown himself was also spotted in a curious position lately after he was seen at the gym without his wedding ring. A source told the Daily Mail, "He drove up in a little blue sports car. He has a twinkle in his eye and a certain charm, I'm sure some of the ladies at the place were checking him out."
"You'd never know that he had four wives and 18 children at home," the source added. "It seems like his wives would want him to wear it, especially at a place where there are plenty of attractive single women hanging out."