The Season 17 The Bachelorette star didn't mention John by name or even clarify that she was talking about her relationship, but fans had been speculating about Katie's romance for weeks considering her last Instagram post mentioning John was back on May 1.
Hours after Katie's brief and to-the-point post, John confirmed his split from Katie on Instagram Stories.
"I love being able to share special moments with you all -- the funny ones. The happy ones. The outrageous, embarrassing, and heartfelt ones. But I don't know if it will ever get easier to share the sad ones," John began on social media.
"As Katie stated earlier, we are no longer dating. This decision was not made lightly, and it was obviously not an easy one to make."
He continued, "I appreciate every one of you that has supported us throughout this journey. We could not (and would not) be here without you."
Neither Katie or John provided any context on why they split or what went wrong in their relationship.
Katie and John's breakup appears to have happened very recently because John posted a video of Katie walking their cats together on June 2. She was all smiles in the video and seemed happy.
Katie and John, whom Katie eliminated during Week 2 of her The Bachelorette journey, met in early 2021 while filming the show, but they didn't go Instagram official with their relationship until late November 2021.
Katie unveiled John as her boyfriend late last year by posting footage of John on Instagram Stories set to Taylor Swift's "Begin Again," a song about falling in love all over again.
The John dedication served as the conclusion of Katie's "12 Days of Messy" challenge in which she had been tasked with matching every song on Taylor's re-released "Red" album to one of her Season 17 bachelors.
Katie and the San Diego-based bartender revealed in April 2022 that they were living together at Katie's apartment in San Diego, and they gushed on the "Off the Vine with Kaitlyn Bristowe" podcast that same month how they were madly in love.
Katie, however, said of possibly getting engaged at the time, "Look, the last thing I need right now is any kind of engagement. I am very, very content with where I'm at in my relationship with John."
Katie had said she didn't "feel pressure at all" for John to pop the question.
"I don't think there's pressure. But I definitely think people ask it a lot," Katie told Kaitlyn about a John engagement.
"Because they are so used to a very quick engagement. So in their minds, they're like, 'So when are you guys getting engaged?' But in the normal world when you aren't on a dating show, it's not normal to ask that after just a few months."
John previously admitted his nerves got the best of him while filming The Bachelorette and so he didn't make a good impression on Katie, who thought her initial conversations with John were "robotic" and rehearsed.
Katie therefore got engaged to wildlife manager Blake Moynes during her The Bachelorette season finale, which filmed in April 2021 and aired in August last year.
Katie and John went public with their romance only three short weeks after Katie and Blake announced in late October they had split and decided to end their engagement.
Katie faced backlash for having moved on from her former fiance too quickly with a "rebound," and Blake said on the "Talking It Out with Bachelor Nation" podcast in November that he felt "flabbergasted," shocked and "speechless" upon finding out about Katie's romance with John.
Blake also said he believed Katie had been emotionally cheating on him with John -- which Katie and John have both firmly denied in the press.
Katie admitted she and John considered hiding their relationship at first in fear of how Bachelor Nation might react to them.
"We were already talking about how to not be [seen and] known. But it's also like, 'F-ck that.' I want to live our best life. I want to live in my happiness. I went through hell and back being on TV," Katie said in April.
Katie said she had determined that she owed it to herself to be in her "truest" and "happiest form."
"At the end of the day, I was like, 'Life is too short. I've gone through so much and I just want to be happy.' And so that's ultimately what we did; we owned our connection not knowing it would take us to this day," Katie told Kaitlyn on her podcast.
The former bank marketing manager and John, in addition to living together, also bought a van together earlier this year so they could drive across the country and explore new cities together.
"John makes me want to be a better person, and he challenges me... He's very energetic and he keeps me young. He says I have the potential to be adventurous... and he makes me want to go and try new things," Katie recently shared.
For Blake's part, he told Ben Higgins and Ashley Iaconetti on their "The Ben & Ashley I: Almost Famous Podcast" in February that he was ready to begin dating again, but only in the real world and not on Bachelor in Paradise.
"I could probably talk to her and have a cordial conversation," Blake, who initially felt blindsided by Katie and John's romance, confirmed in late March.