Entertainment TV Birthday Girl Kendall Jenner Is 'Serious' About Boyfriend Blake Griffin, Source Says By Michele Corriston Published on November 3, 2017 01:30 PM Share Tweet Pin Email Basketball player Blake Griffin is keeping up with the Kardashians more and more as he courts Kendall Jenner. The NBA star joined her family — including parents Kris Jenner and Caitlyn Jenner and sisters Kourtney Kardashian and Kim Kardashian West — at her birthday dinner at Petit Taqueria in Los Angeles on Thursday night. “Kendall was in a great mood,” an onlooker tells PEOPLE of the supermodel, who rocked $10,000 Saint Laurent boots at the bash, sponsored by Tequila Avión. “She and Blake hung out, but they also mingled separately.” Splash News (2) Another source adds: “Kendall is very happy with Blake. They started out more like friends, and then it was very casual. But it seems more serious lately. When they are not together, they keep in touch over the phone. Her family has accepted Blake. They are spending time getting to know him.” Splash News Kendall, 22, and Griffin, 28, have been hanging out since August — shortly after the Los Angeles Clippers power forward split from the mother of his two children, Brynn Cameron, a former college basketball player. Kendall was recently seen cheering him on at a Clippers/Lakers game Oct. 19, and hanging with him at a Halloween party.