"Scott proposed to Kourtney," a Kardashian source revealed to Us Weekly. "Not with a ring. He just said, 'Let's get married.'"
The 37-year-old Keeping Up with the Kardashians star has dated Disick on and off for about a decade and the couple has three children together, but still, "She told him no," according to the source. "Scott was embarrassed, upset and angry."
The root of the pair's problems most often appeared to be Disick's partying ways, drinking habits and failed rehab stints.
When living that lifestyle, Disick also made mistakes -- like when he was caught getting touchy-feely with ex-girlfriend Chloe Bartoli in Monte Carlo in July 2015, when Kardashian dumped him for good after fighting for the relationship for years.
Disick, 33, was reportedly in distress over Kardashian's jilt in Costa Rica because he's been working hard for two years to get sober and be a good father for Mason, 7, Penelope, 4, and Reign, 2. For example, he'd only spend time in clubs when he was hired for hosting gigs
However, Disick's efforts to win his longtime love back were wasted, as his pal told Us, "Kourtney is over being with him."
Disick allegedly flipped out and secretly flew another woman to Costa Rica to keep him company, which was the widely-reported reason he and the Kardashians got into an "explosive fight" while on their tropical getaway. Disick allegedly rented a room at the hotel where the KUWTK production team was staying for the mystery woman.
"Kourtney is not upset he's seeing other women. 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," a show insider told the magazine, although a Disick friend argues his decision was set up for the show.
One day before the Kardashian family's vacation was scheduled to end, Disick reportedly flew to Miami to party with model admirers, including Jessica "J Lynne" Harris and Amber Davis.
He was caught making out with Harris at the Setai hotel pool on January 30, according to Us, and spotted snuggling with Davis the following day on a poolside lounge chair.
"This is all a 'f-ck you' to Kourtney," said the Kardashian source. "But she doesn't care. She's done with all of it."