On Friday, TMZ published photos of the 35-year-old Disick having arms around a mysterious, green-eyed blond woman. Sources told the site they were "flirty" and had their hands on each other during two of West's songs.
Disick was described as "wasted" during the event and telling friends he is single. He was reportedly "rarely" without a drink in his hands. A source told Us Weekly Disick was "really sloppy throughout the night" and "could barely speak" at West's event.
He took a few friends and his own security to the event, but the 19-year-old Richie was nowhere to be seen. She posted from the Nobu restaurant in Malibu, a thousand miles away from Wyoming.
On Saturday, a source told Us Weekly that Richie and Disick, the father of Kourtney Kardashian's three children, split up after she learned he cheated on her in Miami. She told her father, music legend Lionel Richie, who threatened to write her out of his will if she continued seeing him.
The couple went to St. Bart's earlier this week to celebrate Disick's birthday and their one-year anniversary. When they got home, Richie found out about Disick's affair with a women in Miami, which "caused huge problems in their relationship."
"He went to Wyoming because of it and was photographed with another girl and that was the icing on the cake for her to break up with him," the source said.
Us Weekly's source said the couple tried to keep their relationship alive, but Richie's father is forbidding his daughter from seeing Disick. Another source told InTouch Weekly that Lionel wants to see his daughter date someone more age-appropriate.
A source for PEOPLE said Disick "seems fine" and "even thinks she might change her mind. He isn't really taking it seriously."
"When Scott drinks, he is a sloppy mess and fools around," the source told PEOPLE, adding that Disick's "old issues" played a role in the breakup.
Disick and Richie started dating in 2017, after they were seen together at the Cannes Film Festival. They confirmed their relationship in September, and frequently posted photos of themselves together on trips to Mexico, Italy and other hot spots.
Disick previously dated Kardashian from 2006 to 2015. They are parents to three children, Mason, 8, Penelope, 5, and Reign, 3. Kardashian is now dating model Younes Benjima.