"You were the last thing I ever expected @derekjacobkesseler," Kaitlyn, 24, captioned the image on her Instagram Story.
Kaitlyn was evicted from the Big Brother house on July 26 after spending four weeks in game. As for Derek, 27, he finished in third place during his season earlier this year.
When Kaitlyn, a life coach from New York who currently resides in Encino, CA, entered the Big Brother house in June, she was in a long-term relationship with DJ Joe Pincus.
During the game, however, Kaitlyn was accused of manipulating and flirting with men in the house despite having a serious boyfriend back home. (Sam Bledsoe even called Kaitlyn's gameplay "cheap" and said she disrespected herself and others).
Kaitlyn admitted to fans on Instagram Live in late July that she and Joe were "taking a little bit of space."
Kaitlyn also seemed to have a crush on her "best friend" in the house, Faysal Shafaat.
Joe, however, had made it known while Kaitlyn was playing the game this past summer that he didn't appreciate Kaitlyn's antics in the house. In fact, he released a statement on Twitter, suggesting he was done with his then-girlfriend of five years.
"I tried to stay silent but clearly that isn't an option as I've been overwhelmed with the volume of everything on TV and social media. I've been trying to separate myself from the show and the situation as much as possible," Joe wrote.
"I did indeed request (not demand) for [my] 'show release' to be pulled, and that is still to be determined (I'm aware people in past seasons have done this). All other accounts reporting 'insider info' are lying to you or twisting a story."
Joe refused to comment any further on his girlfriend's actions, except for saying he'd be "focusing on my family and friends, wellbeing and my music" going forward and he was thankful to the people who were "not pushing a false narrative."