90 Day 's Kim Rejects Usman's Mom's Demand He Marry Another Woman First: 'Not Gonna Be Anybody's Second'

90 Day Fiancé: Happily Ever After? star Kim Menzies won't accept anything less than first priority when it comes to her marriage Usman "Sojaboy" Umar.

In an exclusive sneak peek at Sunday's episode, the 52-year-old Californian is shocked after Usman's mother says he can't marry Kim — at least not before taking a younger wife.

Usman, 33, and Kim leave the unfortunate family meeting in Nigeria feeling sad and angry, but Kim is set on proving her worth. In follow-up conversations with Usman, Kim is vocal about why she deserves to be his first wife and reminds him she won't take a backseat to anyone else — even a younger woman who can bear children.

It's Usman who speaks of the encounter first, after he admitted to his family that Kim would allow him a second wife for the purpose of having kids. "I was thinking that would touch them," Usman said. "But they just turned it upside down."

RELATED: 90 Day Fiancé: Usman's Mother Denounces Kim for Buying Them a Cow as a 'Bribe' to Bless Marriage

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He points to his Nigerian culture and his family's expectations. "What I'm saying is that we have certain culture over here that you can never go against, too. But I hope you have seen how much I love you. And you know how my mom is to me. You know how I see my mom. I think after God, I see my mom second God to me."

Usman reveals he can't go against his mom's wishes, and tells Kim he'll marry another woman before Kim. "Then it's over," Kim says. "I'm not gonna be the second wife. I can't. I can't let myself be like that."

Kim says she respects Usman's mother, but it's against her own nature to take a back seat to any other wife. "I won't be anybody's second anything," she adds.

RELATED: 90 Day Fiancé's Usman and a Female Friend Trigger Kim's Insecurity: 'She's Everything I'm Not'

Kim explains later in an interview why this is a dealbreaker. "It's like his mom was giving me a compromise, but I can't make any more exceptions because I have exactly what I want now — his love. I feel like the love he has for me now will change with that."

Kim compares it to relationships past. "Getting the title of the first wife is so important to me because in previous relationships, I always came second. Always. I was always pushed to the side, and I'm not gonna let that happen to me again."

It's the idea of being his second rank that makes Kim want to walk away. "I don't care if he came here and proposed to me right now with the biggest diamond in the world. I'm not his second. Sorry. I can't. I know my worth."

TLC Kim and Usman from 90 Day Fiancé: Happily Ever After

In last week's episode, Kim and Usman told his family they'd like to wed. While seeking his mother's blessing, the family questioned why Usman has now brought two older, white American women home to wed. Though they previously approved of his previous union with Lisa Hamme, this time his family said no.

Before meeting his family, Usman and Kim were aware that a disapproval from his mother could mean the end of their relationship. Whether Usman and Kim will find a way to stay together despite his mother's wishes has yet to be seen.

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90 Day Fiancé: Happily Ever After? airs Sunday nights at 8 p.m. ET on TLC.