Kourtney Kardashian and Younes Bendjima took a big step in their relationship on Wednesday night.

According to a new report, the 38-year-old Keeping Up With the Kardashians star debuted her new clothing line, PrettyLittleThing, at Poppy in West Hollywood, California. During the launch, she was joined by her younger sister, 21-year-old Kendall Jenner, and her boyfriend, Younes Bendjima, 24.

“Kourtney, Kendall and their group of girlfriends all arrived around 10 p.m., and headed straight to a VIP area next to the deejay,” a source told People magazine on Oct. 26. “Younes showed up not too long after.”

“She looked like she was having a blast the entire evening,” the source continued of Kardashian, who wore a stunning black minidress and heels for the debut of her new fashion endeavor.

“She was smiling the whole night, laughing and chatting with her girlfriends. And as soon as Younes showed up, the two kept close and stayed next to each other,” shared the insider. “They were whispering in each other’s ears, taking photos, and at one point, she adorably draped her leg over his.”

During the bash, P. Diddy, whose children have been close with the Kardashian/Jenner family for years, treated guests to a performance, which reportedly wrapped up around midnight.

According to People magazine, a number of celebrities showed up to Kardashian's event to support her, including Full House star Lori Loughlin and her daughter Olivia Jade, Teyana Taylor, Wiz Khalifa, Christina Milian, and Adrienne Bailon.

“Kourtney was sitting on Younes’ lap for part of Diddy’s performance. It was adorable,” the source said. “They looked really happy.”

Earlier this month, Kardashian opened up about her clothing line, explaining that she often got inspiration and confirmation from her sisters, including Kim and Khloe Kardashian and Kendall and Kylie Jenner.

“I see my sisters almost every single day, so while I was designing the collection, if I was going over fabric swatches and they were sitting next to me, I would ask their opinion, like confirming, ‘This is really a good dress,'" she explained.

To see more of Kourtney Kardashian and her family, including her three children, Mason, Penelope, and Reign, tune into new episodes of Keeping Up With the Kardashians season 14 on Sunday nights at 9 p.m. on the E! Network.