The end of an era. Kourtney Kardashian and Travis Barker‘s engagement “is a bitter pill to swallow” for her ex Scott Disick, a source exclusively tells Life & Style.

The Talentless mogul, 38, who shares kids Mason, Penelope and Reign with the founder, 42, “still has lingering feelings” for Kourtney, adds the insider. “After all, she is the mother of his children so it’s only natural.”

Travis, 45, proposed to the former Keeping Up With the Kardashians star on Sunday, October 17, at a beach in Montecito, California. The A-list duo, who took their relationship public in February, was surrounded by candles and hundreds of red roses shaped like a heart. “Forever,” Kourtney captioned the announcement via Instagram.

Following the romantic outing, the mother of three and the Blink-182 drummer joined their loved ones for a celebratory dinner. Although many of the Kardashian-Jenner family members, including Khloé Kardashian, Kris Jenner and Kim Kardashian, were in attendance, Scott was seemingly not invited.

According to In Touch, the New York native wasn’t made aware of the proposal ahead of time. “He found out about the engagement on the internet and was reeling when Instagram and social media blew up over it,” an insider told the publication.

Scott and Kourtney dated on and off from 2006 to 2015. Following their final breakup, the former flames managed to successfully coparent for years. However, their relationship hit a snag when she began seeing Travis in January.

“Scott and Kourtney are friendly in front of the kids and at family gatherings, but behind closed doors, they’ve been secretly clashing for a while and barely talk,” an additional source previously revealed to Life & Style. “The arguing started shortly after Kourt and Travis began dating, and she’s accusing Scott of being jealous that she’s moved on and found love.”

Since splitting from Kourtney, the Flip It Like Disick producer has been in two notable relationships. Scott dated Sofia Richie for nearly three years before calling it quits in August 2020. Later, he settled down with model Amelia Gray Hamlin. In September, Scott and the 20-year-old model broke up after almost a year together.