Tyler and Stassie -- who watched the NBA basketball game with Kylie -- were reportedly "hanging out for a bit" at the game before deciding to "keep the night going" at the popular nightclub afterwards.
"They had met in passing before at a few events in L.A., but this was the first time they truly hung out and vibed with one another," the source told E! News.
While it was unclear whether Kylie joined Stassie for the outing to Hyde, the source said, "Stassie arrived with her friend Kelsey and met Tyler inside."
"They were at the same table at the club and several bottles of Don Julio 1942 tequila and champagne were brought out," the source dished.
"Tyler and Stassie were dancing together to hip-hop music and were showing a lot of PDA."
It appeared the pair were definitely interested in each other and having fun, according to the website.
"He was holding her. They were whispering in each other's ears and talking the entire night," the source revealed.
"It was very apparent they were into each other. Tyler leaned in and kissed her neck at one point, and also definitely kissed her cheek in public."