According to a Kardashian source, she and Bieber “hung out together with friends, but didn’t spend the night together. Kourtney is still serious about making things work with Scott. She went to the birthday party for Cash first and was ready to party more after. They chatted, had fun but that was it. Kourtney is finished hooking up with Justin.”
Kardashian — who bared all in a sheer black lace bustier and silk pajamas for Warren’s ‘pajama jammy jam’-themed birthday affair —posed for a picture with fellow attendees John Legend and wife Chrissy Teigen. Bieber, who returned to Twitter Monday with selfie, opted for a grey hoodie and baseball cap.
Reports of Kardashian, 37, and Bieber, 22, hooking up first surfaced after the reality star ended her nine-year relationship with ex Scott Disick, 33, in July 2015.
Though the two have been spotted on multiple occasions together and were “hooking up on and off for a few months”— sources told PEOPLE at the time that it was never anything serious.
“It’s been a deep flirtation for months. He’s obviously close to the family, and Kris [Jenner] is obsessed with him,” a source told PEOPLE in December 2015. “It’s just one of those things where it makes Kourtney feel good about herself. It’s not serious at all. This young guy is into her, he thinks she’s hot and she’s older. She just wants to have fun.”
Bieber jokingly responded to a headline about his relationship with Kardashian, saying, “I’m being used, man. What can I say?” in an interview on The Bert Show.
Disick followed suit by joking about Bieber and Kardashian during a 2016 episode of Keeping Up With the Kardashians where he and the family played a game of Cards Against Humanity.
Kardashian started things off by posing the question, “Why am I sticky?” and Disick served the ultimate burn by answering: “Justin Bieber.”
News of Kardashian and Bieber hooking up hasn’t always been fun and games to Disick, though, as a source previously told PEOPLE of his reaction: “Of course it stings a bit that Kourt is hooking up with Bieber. But Scott also knows his place and that he doesn’t have the right to have a fit about it.”
The source continued, “He is convinced Kourt is doing it to hurt him. And she succeeded.”
Despite Kardashian’s past with Bieber, she and Disick remain close as they spend time co-parenting their three children— daughter Penelope, 4, and sons Mason, 7, and Reign, 2. The pair most recently returned from a family vacation to Aspen, Colorado together earlier this month.