"He wiped my tears away when I was crying and calmed me down while I was stressed," Kat recalled toUs Weekly.
"Our relationship in the jury house wasn't based on cheap sexual gratification -- it was an actual, genuine friendship."
But the pair's interactions caught on-camera seemed flirtatious, and it became increasingly more obvious romantic feelings were involved.
AfterBig Brother wrapped its 21st season and Jackson Michie was crowned champion, Kat and Nick reportedly spent time together with their fellow cast members in Las Vegas, NV, in September.
Kat, a digital marketing executive, told the magazine she and the therapist then spent a few days together in Los Angeles before he headed back home to New Jersey.
The pair will meet up again when Nick visits Kat in Dallas, TX, where they plan to attend a Dallas Cowboys football game together.
"I'm excited to see him again, especially now that everything is kind of slowing down from the show," Kat said.
Fans were initially surprised to hear about Kat and Nick's relationship in the jury house because she didn't appreciate or support Nick's gameplay on Big Brother. She seemed to think Nick was manipulative and controlling others' decisions.
"If you watched the show, you know that he was not my favorite person in the house and especially during the week I got evicted, but looking back I see that I had a lot of preconceived opinions about his gameplay that I let affect my opinions on him as a person," Kat told Us.
"The Nick I got to know in the jury house is an incredible person and friend."
Nick also had a showmance with Isabella "Bella" Wang during the show, and the former couple said, "I love you" to each other and discussed dating in the real world.
Kat insisted, however, there was "absolutely no hooking up happening" between Nick and herself because she wanted to be considerate of Bella's feelings.
"I would not have disrespected Bella by kissing Nick or doing anything inappropriate on camera," Kat explained.
"But with that being said, keep in mind that Bella already broke up with Nick over Twitter while he was away in the house."
Bella broke up with Nick because she didn't like how he was behaving in the house. Bella especially had an issue with the fact Nick cuddled in bed with Big Brother'sAnalyse Talavera on more than one occasion.
"I understand she was embarrassed that the idea of Nick having feelings for somebody else was publicly aired on the show, but she had clearly moved on before any sort of drama was revealed about us," Kat told the magazine.