Though their Las Vegas move may have been the catalyst for the end of their plural marriage, Robyn reveals there was more than one factor that led to their plural divorce

Robyn Brown is tracing back to the event that she believes led to the demise of the Brown family’s plural marriage.

In an exclusive interview with PEOPLE, the Sister Wives star, 45, reflected on her former sister wives’ Janelle, Meri and Christine Brown and the dissolution of their relationships with polygamous patriarch Kody Brown.

“I think it started with when we were in Las Vegas,” she says, noting that the shift began when their respective adult children decided to leave the nest. “So their focuses started to shift to kids that have left home to go live their life, instead of focusing on their relationship with Kody.”

According to Robyn, the other wives stopped maintaining not only their marriages to Kody — but also to their commitments to each other.

“It started becoming a lot of focus that direction, as far as holidays and things like that,” she adds.

Las Vegas was the start of their growing divide, Robyn says, and once the family moved to Flagstaff, Arizona, the wives became “separated geographically” and “weren’t in each other’s lives as regularly.”

“That made us feel more independent of each other,” she continues. “It was easier just to not spend time together because it was harder to get in the car and go hang out at someone’s house and then try to figure out if you get through the snow to home and things like that. And so I think that was the next step.”

Housing arrangements in Flagstaff and debates surrounding “living in one home or building one home” was the “next step” and “brought out a lot of truths.”

Robyn explains, “I think a lot of the issues that were a part of their past started to come up. It was before I came in the family, there was these issues about living together that started to come up, and they started talking about that.”

Things in their plural marriage only got worse when COVID hit. The reality star shares how the pandemic became a “perfect storm” in their relationships.

“We weren’t as united, and everybody [was] disagreeing about how to handle it. And it became this fight and people were so independent by that point,” she says.

“I think it’s just also kind of an age thing,” she adds. “What I’ve heard, is that you get to a point where you aren’t as interested or care as much, or you just become more independent as a woman in a marriage and as obsessed with or interested as much in maybe your hubby and everything.”

Robyn says that age was a factor for both Kody and the wives.

“I’ve heard them all talk about, ‘Well, I don’t know if I want this anymore,’ or, ‘I just want something different,’ or, ‘I used to be OK with this and how this was going, but now I’m not OK accepting what it’s been,'” she recalls.

Christine and Kody announced their split in November 2021 after being “spiritually married” for 25 years. She has since found love again and officially tied the knot with her now-husband David Woolley in a large Utah ceremony in October.

Despite her shocking split from Kody, Christine has remained close with Janelle, who confirmed her separation from the family patriarch a year after Christine in December 2022. A few days after the news of Kody and Janelle’s split, PEOPLE confirmed that Kody’s 32-year marriage with his first wife Meri was also over.

Meri was the only wife who was legally married to Kody until 2014 when he divorced her to marry Robyn. While Robyn is Kody’s only remaining wife, she still questions their relationship and where it’s headed. Between his former and current wives, Kody is a father to 18 children in total.

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Sister Wives airs Sundays at 10 p.m. ET on TLC.