AceShowbiz -

Scott Disick has "given up" on getting Kourtney Kardashian back. According to an insider, the 33-year-old restaurateur popped the question to the "Keeping Up with the Kardashians" star during family vacation in Costa Rica, but she rejected it.

Scott allegedly vowed that his four-day trip to Costa Rica with Kourtney and their three kids would be unforgettable. "Scott proposed to Kourtney," the insider tells Us Weekly, "Not with a ring. He just said, 'Let's get married.' [But] she told him no. Scott was embarrassed, upset and angry."

According to the insider, Scott had been on a two-year mission to win Kourtney back, getting sober at a Malibu rehab in 2015 and visiting clubs only for paid hosting gigs. Unfortunately, "Kourtney is over being with him," says a Scott pal.

Following the heartbreaking rejection, Scott reportedly flew another woman to the Papagayo Peninsula, then holed up with her in the production team's hotel. "Kourtney is not upset he's seeing other women," says a "KUWTK" insider, "She's upset he'd disrupt the trip with the kids. If you're dating someone important, bring her to meet the family. Don't hide her." His pal, however, insists that his antics were set up for the show.

Scott then flew to Miami for a week of binge drinking with some women. The insider says, "This is all a 'f**k you' to Kourtney. But she doesn't care. She's done with all of it."

Another source tells PEOPLE that Scott "was working to get Kourtney back but has given up again." The source adds, "Kourtney hasn't been happy with Scott for weeks. It has nothing to do with what he is doing in Miami right now. She just doesn't like when he parties. He is an irresponsible dad when he parties. She is not happy with Scott. She allowed him to come to Costa Rica for a couple of days so he could have fun with the kids. Partying and making out with different girls publicly isn't exactly the best behavior when you are a dad."