The Bachelorette captioned the footage, "@desireesiegfried knew exactly what @thekatiethurston was going through."
In the deleted scene, Katie was shown waking up in bed the morning after Greg quit the show because he claimed Katie hadn't given him enough validation and reassurance that their relationship and their love was "real."
Katie said she was feeling "hurt, sad and confused" and a part of her was still processing what happened.
"Greg is someone I thought we'd make it to the end together. It's just hard," Katie lamented at the beginning of the video clip. "Every time I become optimistic, it backfires on me."
Katie decided she wanted to talk to Desiree, who "went through something similar" when Brooks Forester chose to leave the show near the end of the series' ninth season.
Brooks decided to quit The Bachelorette 9 at the very beginning of his final one-on-one date with Desiree in Antigua.
The suitor determined he wasn't madly in love with Desiree, and although his feelings for her were strong, Brooks acknowledged they weren't where they needed to be at that point to consider asking for her hand in marriage.
Katie explained to Desiree on the call that she was down to her Final 3 bachelors.
"Yesterday, Greg, who I truly thought was going to meet my family, chose to leave," Katie revealed.
Desiree, a 35-year-old former bridal consultant, replied, "Oh shoot," and asked Katie why he chose to leave prematurely.
"Did he say why he decided to leave?" Desiree questioned the Season 17 The Bachelorette star.
"And that's the hard part," Katie explained. "He was in love, he told me he saw himself down on one knee but he didn't think that I could give him enough. I'm sure that's how you felt when your person left."
Katie went on to ask, "Do I owe it to myself to keep going? Because it feels so confusing."
"Girl, I was there," Desiree confirmed. "I mean, I kept trying to hold onto a relationship that I constantly had to reassure. And then he ultimately left. So I think the fact that he didn't stay kind of shows, I don't know."
Desiree suggested Katie isn't meant to be with a man who would give up and quit on her.
"You want a man who's going to stay for you no matter what, but you also don't want someone who's going to walk away at hard things," Desiree reasoned.
Desiree also shared with Katie how she never said "I love you" to anyone on her season until the Final Rose Ceremony, when she selected Chris as her winner and he proposed marriage.
"[Chris] was so confident in us because he knew, like, in his heart, he was there for me, regardless," recalled Desiree, who is still happily married to Chris today.
"I will say, that is the biggest quality you want in a husband and a dad. I've been married six years... two kids. Yeah, it worked out. It worked for me, but I think it's really important to keep going -- and anything can happen."
"Everything has happened!" Katie responded. "It's crazy!"
Katie subsequently said in a confessional it was "reassuring" to hear that someone else -- who had been in her shoes -- struggled in the same manner during the show's process.
"After talking to her, I feel confident about staying," Katie concluded in the clip. "I've gone through a lot and it'll all be worth it, to have that beautiful love story at the end."
After pouring his heart out to Katie and saying she had filled a hole in his heart, Greg angrily left the show because Katie wouldn't acknowledge his declaration of love or express her own feelings in return.
Greg scolded the Bachelorette for treating him like "a number" and being more focused on the show and giving out roses than on the authenticity of their relationship.
During a recent appearance on The Viall Files podcast hosted by former The Bachelor star Nick Viall, Greg apologized for how he had treated Katie during their breakup conversation, especially for leaving Katie on her knees crying.
"I came off like an ass. I came off like a petulant child," Greg confessed. "And I regret it, because at the end of the day, she didn't deserve that."