The three celebrated with friends and other members of the Keeping Up With the Kardashians family, including her mom Kris Jenner and sister Kendall Jenner, at a bowling alley about 15 minutes from their Los Angeles-area homes. Kourtney and Scott were photographed arriving separately at the party, which took place in the late afternoon. She arrived with their younger children, daughter Penelope, 5, and 2-year-old son Reign.
"Scott arrived to Mason's birthday alone with gifts in hand, and him and Kourtney were cordial," a source tells E! News. "The space was very big and spread out so they didn't have to interact much. Kourtney didn't ignore him, but wasn't overly chatty and was just happy he showed up for Mason."
The insider also adds that Scott "was hanging out with Kris and Corey Gamble for a while but was also paying a lot of attention to Mason and his other kids. He was truly acting like a parent and taking initiative which made Kourtney happy."
IXOLA / BACKGRID. Rachpoot/MEGA.
There were over 60 people at the party, which was rented out until 7 p.m. "They had endless pizza, chicken fingers and fries," the source shares. "Mason loves the arcade games and was having a lot of fun with his friends."
Kourtney and Scott have been broken up for 2 and 1/2 years. They have rarely been spotted together in recent months. Before Friday, they were most recently photographed together with their kids on a family trip to Disneyland in mid-April.
Kourtney's beau Younes Bendjima and Sofia Richie, the model Scott has been dating, were not spotted at Mason's birthday party. Based on her Instagram Stories posts, she appeared to have had a relaxing evening at home.
After Mason's party, Scott and Mason were photographed together at a seafood restaurant near the family's homes.
The two recently went on a father-son trip to New York and Miami over Thanksgiving.