You, Me & My Ex Sneak Peek: Caroline Questions Boyfriend Alex's Close Bond with His Ex Stephen

TLC's latest series You, Me & My Ex will explore the close bonds people have with their exes, despite being involved in new romantic relationships.

In PEOPLE's exclusive sneak peek at Sunday's premiere, audiences are introduced to Caroline and Alex - a couple who met at work, where Caroline would advise Alex on his relationship with now-ex-boyfriend Stephen. Despite Stephen and Alex's split, they have remained close and continue to talk to each other daily, which raises concern for Caroline.

"It's so weird to go from, like, literally him talking about Steve, his ex, and wanting relationship advice to all the sudden it being kind of the opposite of, 'Well, no, you're with me. Why are we still talking about Steve?'" Caroline says in a confessional.

Some time after the former couple called it quits due to Stephen's infidelity, Alex "went from being Caroline's gay best friend to her boyfriend," a show description from TLC reads. "He had a hard time feeling accepted throughout his life, and now he and Caroline struggle with others not understanding Alex's fluid sexuality and their relationship."

TLC Caroline, Alex and Stephen

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In the clip, Caroline and Alex get ready in the bathroom together, where he accepts a call from Stephen.

"Alexander, he's the first person I ever said 'I love you' to," Caroline says of Alex. "At the beginning, I think there were still some insecurities within myself. It's draining, the feeling of are you suddenly going to wake up and decide, 'You know what, actually I really just don't like vagina anymore.'"

TLC

For Caroline, she says that the struggle is largely an "internal" insecurity for her where she questions whether she's enough for Alex.

However, she feels as if she's "kind of let that go."

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TLC Caroline, Alex and Stephen

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The series will also introduce viewers to four other complicated dynamics: Jerry, Kayee Lovey and Jerry's ex-wife Jessica; Jimmy, Wendy, Jimmy's ex-wife Lisa and Lisa's fiancé Jack; Josh, Danielle, Josh's ex-wife Jennifer and Chantel, Jennifer's wife; and John, April, John's ex-wife Loren and Roy, April's ex-husband.

You, Me & My Ex premieres Sunday at 10 p.m. ET on TLC.