The Bachelorette Season 17 star and Blake, who proposed to Katie after she selected him as her final bachelor when the season's finale aired on ABC in August, announced their breakup in a joint statement posted to their Instagram accounts Monday evening.
"It is with mutual love and respect that we have decided to go our separate ways," the pair wrote.
According to their statement, Katie and Blake have concluded they are "not compatible as life partners."
"We are so grateful for the moments we shared together and the entire journey that has unfolded this year, but we ultimately have concluded that we are not compatible as life partners, and it is the most caring choice for both of us to move forward independently," they wrote.
The pair ended their brief statement asking for kindness and privacy.
"We ask for kindness and privacy as we both navigate this transition," the statement concluded. "Both of us will forever want the best for one another and ask you to please support us in our decision."
The couple's sudden split announcement came only days after Katie admitted she had been "totally winging" her relationship with her fiance Blake following their televised engagement.
"I'm, like, totally winging my life right now," Katie, who recently moved to San Diego, CA, told Us Weekly of her excitement to reunite with the Toronto, Canada native before she performed at a comedy show in Anaheim, CA on Friday night.
"I literally leave tomorrow in San Diego at, like, six in the morning. So I'm driving back home after [the comedy show] at some point," Katie said.
During the interview, Katie -- who originally competed for Matt James' heart on The Bachelor's 25th season -- sounded somewhat indifferent about her relationship with her fiance, a wildlife manager who has been in Africa rescuing rhinos recently.
"We're figuring it out," Katie said of her romance with Blake. "We don't know. This is very new to us still. I'm just focusing on myself, he's focusing on him, and if we work doing that, great."
Katie had added she was most looking forward to a time when she and Blake could stop "traveling back and forth" and stated she'd like to settle down with Blake "eventually."
The couple's split announcement also comes less than two weeks after Katie had taken to Twitter and clapped back at speculation she and Blake had broken up.
On October 15, Katie tweeted a screenshot of one of her recent Instagram comments that read, "You and Blake are not liking each other's posts. Is all OK?"
The screenshot showed that Katie immediately responded to the fan, "Yes," with a tears-of-joy emoji.
Katie tweeted alongside the image, "Imagine your fiance has been on his [Instagram] stories for weeks in Kenya working his ass off and yet this is what some people notice," in addition to another tears-of-joy emoji.
One of Katie's followers wrote, "But 'liking' posts = love I thought," to which Katie replied in a snarky manner, "I guess that's love in 2021."
"It's hard to say the impact of that in the real world, [if he didn't propose], because you go through so much and you want to take this very seriously -- and a proposal and engagement is very serious," Katie explained at the time.
"I didn't come here to find a boyfriend. I can do that on a dating app," she added. "So it's hard to say if we would have survived just as a dating couple."
Katie said her relationship with Blake had strengthened once they promised each other forever.
"The fact that we're both committed to each other as future husband and wife, it just says a lot about our confidence in our relationship," Katie said.
The former bank marketing manager and Blake also spent time together in New York City in September.
"I don't think people fully understand what it's like to date someone from another country and the rules behind that and the visas behind that," Katie said in a series of late-August videos posted to her Instagram Stories.
"I think right now Blake can only be here for 60 days before having to go back to Canada," Katie continued, seemingly referring to how a Tourist Visa works.
"So we really do have a lot we have to look into -- and we just haven't yet -- before we can plan really anything else."
Once Blake left for Africa to continue his endangered-animal conservation efforts, Katie reportedly wrote on Instagram earlier this month, "It can feel lonely moving to a new state... I've had trouble sleeping lately... I'm still trying to navigate this new life and city while seeking normalcy."
Katie and Blake had said they were in no rush to wed and intended to travel together and learn more about each other's backgrounds, interests, hobbies and hometowns before deciding on an "anchor spot," or city in which to put down roots as a couple.