Along with forgetting to wear her ring, Evelin mentions that she wants her boyfriend Corey to lose weight before they tie the knot

What’s a fiancée without an engagement ring?

PEOPLE has an exclusive sneak peek of Corey Rathgeber and his Ecuadorian fiancée Evelin Villegas on Monday’s 90 Day Fiancé: The Other Way’s “tell-all” episode. With a handful of months left before their wedding, Shaun Robinson asks the couple what’s holding them back.

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“So Evelin, within six months, you and Corey are going to be husband and wife,” says Robinson, 52, after Rathgeber, 31, assures the host they’re getting wedding prep rolling.

“I hope. I don’t know, I just don’t know,” Villegas, 26, responds hesitantly. “Like how are we supposed to plan our wedding and things that needed to be figured out in such a short time?”

Rathgeber then justifies Villegas mentioning some of the worries holding Villegas back from tying the knot — including him losing weight.

“And I know you’ve asked me to learn Spanish,” he says. “She’s asked me to talk with her family and immerse myself in the culture more.”

“And she says I need to put on more muscle like I need to look more attractive,” he continues. “I need a six-pack and then we can get married.”

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Villegas laughs, saying, “Yeah, it’s because he got a lot of weight on.”

Since asking for him to become more muscular, she adds that “he started nothing” to get there.

“I still have five months because I was accepted for a six-month extended tourist visa,” he defends himself. “Meaning it gives us the extra time necessary to get the ball rolling with the marriage.”

Robinson then changes the conversation, asking Villegas to hold her hands up to the camera.

“Are you wearing your engagement ring?” she asks.

Villegas slowly puts up her bare hands, only adorned by a hair tie around her wrist. Villegas starts laughing. “I forgot,” she says.

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“Seriously, Evelin?” Rathgeber asks, putting his own hands to his face in dismay. “Are you kidding me?”

“I forgot, I completely forgot,” she responds.

As the two discuss with Robinson, the other cast members of 90 Day Fiancé: The Other Way watch in a separate room.

“If Sumit put a ring on this finger, it would never come off,” says Jenny Slatten of her own Indian fiancé. ”Not ever. I would superglue that thing to my finger and it would never come off.”

Amid pockets of awkward silence and questioning faces from the host, Rathgeber says, “I can’t believe you’re not wearing it right now, Evelin. What the heck!”

“I’m so sorry,” she replies. “I literally just realized it this morning and I was like ‘oh no!’”