On Sunday’s episode of ‘Sister Wives’, Robyn Brown said she “never understood why” Christine Brown didn’t want to have a relationship with her

Christine Brown and Robyn Brown are opening up about their complicated relationship — or lack thereof.

The Brown family heads reflected on the early beginnings of the tension among them during Sunday’s episode of Sister Wives. In doing so, the conversation shifted specifically toward the issues between Christine and Robyn.

The two TLC personalities’ opinions differ regarding the time Kody spent at all the wives’ homes, with Christine claiming that Kody prioritized Robyn and Robyn suggesting that was just an “assumption.”

This issue caused strain between the pair, with Christine insisting she couldn’t “trust someone who says they want family yet they are fine with Kody only being at their house.”

“I always thought that eventually, she would open herself up to a relationship with me,” Robyn, 44, told Meri Brown, 52. “You know, figure that stuff out. You know, figure out whatever her issue was. I tried very hard to be kind with her.”

Robyn then told the cameras that she was “constantly holding out an olive branch to Christine, constantly wanting the relationship, constantly trying to ask her, ‘What can I do?'” But Christine, 51, allegedly only ever said in response that she was “just jealous” of Kody’s fourth wife.

“There’s so many times where Christine and I have had so much fun,” Robyn continued through tears. “I feel like we really did have the potential of just having a great relationship, and I just never understood why we couldn’t. And I just don’t know how to come to terms with the heartbreak of it.”

But Christine felt justified for not wanting to have a close relationship with Robyn.

“[When the family lived] in Vegas, we all did counseling sessions together. All the adults. In the therapy sessions, I was very direct and I said specifically the problem is [Kody] prefers Robyn and prefers being in Robyn’s house more than anywhere else,” Christine said in a confessional. “She would just deny it and she’d just be like, ‘He’s not here.’ And he’d be like, ‘I don’t know what you’re talking about. I’m over at your house equally.’ And I was like, ‘No, you’re not. No, you’re not.'”

Christine continued, “If it bothered her that she didn’t have a relationship with me, she should’ve said, ‘Hey, why don’t we have a relationship? Can we be friends? But I want you to know, I would’ve rejected her friendship anyway, to be completely honest with you.”

Christine added for emphasis: “Because I couldn’t trust her.”

Christine also called out Kody for suggesting she was not a good sister wife to her now ex-husband’s three other wives.

“I was a gracious wife to Janelle [Brown]. Meri, not so much. But I don’t think he cares about Meri. He’s basically saying because you’re not the best sister wife with Robyn, I’m not interested in having a relationship with you,” Christine said in a confessional. “Hmm, who had a great relationship with Robyn for years yet he wasn’t attracted to her? Oh yeah, that would be Meri. He’s full of s—, I’m sorry. That’s ridiculous.”

Kody, 54, begged to differ, saying in a separate confessional that “it wasn’t ever really about Robyn, it was about her whole experience in plural marriage with other wives.”

Robyn is now Kody’s only wife after Christine, Janelle and Meri all left him in less than two years. The ongoing family fallout has been a focal part of the TLC show’s 18th season, which is beginning to show the demise of Kody’s marriages with first wife Meri and second wife Janelle, 54, as he enters a dark place.

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.