Nikki spoke her mind about Clare and didn't hold back during a recent appearance on The Bachelor alum Nick Viall's The Viall Files podcast.
"I just don't think she's, like, emotionally stable," Nikki, 33, said of Clare, who memorably lashed out at Juan Pablo after the former pro soccer player denied her the final rose on his The Bachelor season.
"I don't really know what's happening. I don't really have an inside scoop, you know? But I just think it's going to be weird, like, did you really fall in love with a guy in two weeks? Like, really?!" Nikki said.
"I don't know, maybe she did. And everyone deserves love, so [if she did fall that fast], good for her, I'll pray for him."
Nikki admitted everyone deserves love although she has never cared for Clare.
"I just think it's all really strange... I don't even know if I'll watch [The Bachelorette this year] because her voice is kind of like nails on a chalkboard to me... She's just a little nutty. She's just a little crazy," Nikki said of Clare.
Nikki also said in her interview with Nick that while she doesn't hate Clare, the women are not friends and will never be friends. Nikki said she simply doesn't care about Clare and assumes Clare feels the same way about her in return.
Given Nikki wasn't afraid to speak her mind or stir the pot a little bit, Nick joked it's a shame Nikki never appeared on Bachelor in Paradise.
Nikki revealed producers had approached her about a stint on Bachelor in Paradise some time after she and Juan Pablo broke up in October 2014 -- but she immediately turned down the opportunity.
"[Producers] did ask me to go on Paradise, and I still was very bitter about production at that point and was like, 'Absolutely not, look what you've already done to my life!' But in reality, it wasn't them that did it; it was that relationship and it was [Juan Pablo]," the nurse explained on The Viall Files.
"At that point, they weren't helping, but I do think I was hard on [production]. I was really hard on them. I was so bitter and hateful towards them."
Nikki, however, went on to have a serious relationship with an old friend, Tyler VanLoo, who proposed marriage to Nikki in January 2016. The couple got married in October 2016.
"My husband and I, we knew each other before [I went on The Bachelor]. We were really good friends for several years and we actually kind of semi-dated on and off. It was never good timing," Nikki revealed.
"I'd always, like, break up with a boyfriend and went running back to him. I wasn't a good human to him, honestly. So he had stuck by me through a lot of stuff."
Nikki's relationship with Juan Pablo was highly-publicized and criticized after their time on The Bachelor's 18th season, which featured an anti-climactic ending in March 2014 in which Juan Pablo told Nikki, "I like you," and offered her nothing but his final rose.
After appearing on VH1's Couples Therapy together, Juan Pablo and Nikki split in late 2014.
Rumors swirled at the time Juan Pablo couldn't communicate his feelings for Nikki and allegedly used her for the fame of their celebrity pairing.
Nikki told The Bachelor host Chris Harrison in January 2015 that she didn't feel like she was one of Juan Pablo's top priorities and they're just "different people."
Many The Bachelor fans strongly disliked Juan Pablo during his season for how he treated the women, and those negative opinions spilled onto Nikki for choosing to be with him despite those obvious flaws.
Nikki admitted to Nick on his podcast that nothing could have prepared her for the backlash and so many The Bachelor fans were mean to her and said hurtful things.
"I feel like I haven't told my side of the story in so long because I was still protecting him," Nikki said of Juan Pablo.
"It's been kind of good to be like, 'Hey, he's not a bad guy.' I know everyone thinks he's this terrible monster, but he's not. Is he a little bit of a douchebag? Yeah. But it was just weird circumstances he didn't understand when he got into it, and I wish I stuck up for myself a little more in hindsight."