Zach insisted he's ready to find his person and commit to one woman forever, but Rachel had accused him of not being ready for marriage off-camera in their Fantasy Suite on The Bachelorette's nineteenth season.
"She was four months older [than me]," Zach, 26, told Jennifer Hudson during a Friday appearance on her talk show.
"Well, I was 25 at that time when we had that conversation. So what I have to say is I'm 26 now," he quipped, "so I'm ready."
Zach also shared with the former American Idol finalist how his celebrity crush is Dua Lipa, he eats mustard on pancakes, and his family nickname for him is "Roo," short for "Zacharoo."
Zach fell hard and fast for Rachel on The Bachelorette. He said he pictured the flight instructor as "the future Mrs. Shallcross" and gushed to the cameras about how he was madly in love with her.
But Zach was thrown for a loop in his Fantasy Suite with Rachel, who allegedly became guarded and skeptical of whether Zach was ready to get engaged given his age.
"It's like we were two strangers... Rachel's concern came out of nowhere. And I think it was bullsh-t, to be honest, and she was putting on a front," Zach said on the show.
Zach called Rachel's concerns about his age "a complete blindside."
Zach, feeling shocked and brokenhearted, said his relationship with Rachel had done "a 180" and she was "inauthentic" and totally unlike herself in the Fantasy Suite.
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Once Zach confronted Rachel about their awkward date and how it was clear he wasn't going to be her person, he self-eliminated at the Final 3 Rose Ceremony. He essentially beat Rachel to the punch before she could deny him a rose.
"It's kind of hard to wrap my head around it. I did really love you. I saw a future with you, but I need to go," Zach said.
Zach thought Rachel's behavior towards him was "cold," and he said on the show that he thought he "meant more" to her.
"One of the things I fell in love with was she made me feel, like, special. And I cared for her and I question if any of that was real or if that was just an act," Zach lamented in a confessional.
Zach apologized to Rachel on Part 1 of The Bachelorette finale earlier this month for letting her feel like he had questioned her character. Zach said that was never his intent, and Rachel also apologized for dragging Zach through an overnight date when she got the clarity she needed that night.
On The Bachelorette: After the Final Rose, Zach said he's "absolutely" prepared to give love another shot after Rachel crushed his heart. Zach told Jesse that he spent time with his family after The Bachelorette, regrouped and centered himself.
"I really needed to take some time away and reflect and heal that broken heart, but really, what I learned from that experience was that I didn't change how ready I was," Zach shared.
"I am now more ready. That was almost fuel to the fire. I am ready to find my person and my best friend, and that breakup didn't deter it... I really want to walk away from this with someone for the rest of my life."
Zach went on to meet a handful of his bachelorettes on After the Final Rose, and he expressed how his journey was already off to a great start.
In a departure from the show's traditional early January debut date, Season 27 of The Bachelor will not premiere on ABC until Monday, January 23, 2023 -- about three weeks later thanThe Bachelor has historically begun airing on the network.