Meet the couple who opened their 11-year marriage to a divorced father so they could grow emotionally and sexually

• Kim, 37, and Dustin, 42, have been married for 11 years and opened up their marriage last year.
• On TLC's upcoming series "Seeking Brother Husband," they show their relationship with Vinson, who dates Kim but not Dustin.
• They said opening their relationship has been challenging, mainly due to others judging their decision.

Kim loves Dustin, her husband, and Vinson, her boyfriend, and that's exactly why she wants to find another partner. 

A year ago, Kim and Dustin decided to open their marriage, specifically in search of another man. When Kim fell in love with Vinson, who she met through a mutual friend, they, along with her husband, decided to become a family unit. Their grade school-aged children play together, and Dustin and Vinson have become friends. Kim has a sexual relationship with both men.

Their story is featured on TLC's series "Seeking Brother Husband," where married women seek to date and marry men in addition t0 their first husbands. On the show, partners grapple with jealousy, confused and unsupportive family members, and lots of uncomfortable conversations about polyamory.

During the first episode, Kim, a teacher, and Dustin, a massage therapist, already share a connection with Vinson. But Vinson is wary about bringing a third man into their dynamic, which they confront on the show.

Insider caught up with Kim and Dustin, who said they're nervous but excited about being on the TLC series because haven't publicly shared their open relationship until now.

"We've always worn our hearts on our sleeves, so we were like, 'Hey, let's do this thing,'" Kim told Insider.

She said she hopes that showing her authentic relationships with Dustin and Vinson can help others who are considering non-monogamous relationships.

They opened up their marriage to grow emotionally and sexually 

From the time Kim and Dustin started dating in their 20s, they were comfortable talking about attraction and how it can exist, even outside a marriage, Kim said.

When Kim would point out another man she found hot, or Dustin did the same with a woman, neither grew resentful because they were confident in their connection to each other, she said. Still, they didn't discuss opening their marriage until they hit the 10-year mark.

"If you would've told me early on in our relationship that we would be here, I would have a hard time believing it," Kim told Insider. She said that that foundational period prepared them for the transition to polyamory.

Dustin said he and Kim have always been invested in each other's individual spiritual growth, which to them includes sexual and emotional growth. Taking a leap into an open relationship felt like a way to "to expand and to experience life," Dustin said.

Kim said opening up their relationship made their already great sex life even more lively.

"Feeling safe expressing our sensuality in whatever ways we want helps us be even more sensual with each other," Kim told Insider.

Kim wants to date more men, but Vinson is concerned it will hurt their relationship

When Kim met Vinson a year ago, she said they had an "immediate" connection. On the show, Vinson, who is 36, said he met Kim after struggling with shame over "two failed marriages." She saw the best in him when he couldn't, he said on the show.

According to Kim, the start of her relationship with Vinson was intense and overwhelming because of her long-held religious guilt. Kim said she grew up in an Evangelical Christian community and was taught it was shameful to be with more than one partner.

During the first episode of the show, Vinson and Dustin both say that they unexpectedly formed a close non-sexual bond over their genuine love for Kim. Dustin said he's open to Kim adding even more partners to their family unit, saying he wants her to experience as much of life as she can.

Currently, Kim and Dustin have a home where they raise their 7-year-old son, while Vinson lives alone and has children from a previous marriage. 

"I think on some level, we're all mirrors for each other, and to be able to learn more about who we are through other people, I think is an incredible opportunity," Dustin told Insider. He said that he learned to have more compassion for himself while navigating this new life stage.

But Vinson said he felt himself starting to withdraw from the relationship because he felt unsure about Kim dating outside of him and Dustin, since he already has trouble with being the second male partner in their dynamic.

"My biggest hangup is accepting where I fit into this dynamic," Vinson tells Kim and Dustin during the first episode. 

What are 'brother husbands'?

"Seeking Brother Husband" comes 13 years after the TLC's head-turning series following a husband with multiple wives, called "Sister Wives," which premiered in September 2010. While "Sister Wives" is about the Mormon religion, "Seeking Brother Husband" is not rooted in religious beliefs.

On the show, not all of the men are legally married to their female partners. That's because bigamy, or marrying someone while already married to someone else, is a federal crime, though certain states have minimal repercussions for partaking. In Utah, for example, someone practicing bigamy could be fined, but will not serve time in jail. 

During the first episode of "Seeking Brother Husband," the focus is on Kim dating other partners. But Kim said she's open to Dustin dating other women and he has in the past.

"We've always been an equal-partner relationship. Everything is 50/50. What I can do, he can do, so as I date, Dustin dates as well," Kim told Insider.

One of the hardest parts of opening up was telling family

In preparation for the "Seeking Brother Husband" premiere, Kim and Dustin told their families about their open marriage and started to post more about it on social media.

Until joining the show, Kim and Dustin kept their lifestyle private, telling only close friends and fellow couples in open relationships, Dustin said. He said he's been laying low since the show finished filming and worries about what viewers will say on social media once the show airs.

Regardless of any outside commentary, he said he's proud of himself and Kim. In fact, some of Dustin's coworkers shared about their own open relationships for the first time after seeing Dustin share his online, he said.

"I've gotten a chance to love myself on a deeper level and to appreciate who I am and the courage that I have. I mean, once you do something like this, not a whole lot scares you anymore," he said.

"Seeking Brother Husband" premieres on Sunday, March 26 at 10 p.m. EST on TLC and Discovery Plus.