Star turns down birthday party organized by mother

The reality star who turned 29 on Thursday, March 17 opted to celebrate his birthday with his girlfriend Blac Chyna and her son, King Cairo instead of his famous family. Rob is apparently still feeling the burn from Kris' absence from his birthday last year.

"Kris really wants to have a big party for Rob at her house tonight, and Rob told her that he was not going to celebrate his birthday without his girlfriend," a source close to the Kardashian family told Radar Online, "Kris told him that she would absolutely like Blac to come, but that she would also have to invite the rest of Rob's family, including all of his sisters."

But Rob didn't think that was a good idea as his girlfriend has been feuding with all of his sisters. The source added, "Rob would just rather spend it with his girlfriend this year. He is not about to have his birthday turn into a dramatic situation, or an opportunity for Kris to let cameras roll on Kylie and Blac Chyna's first face-to-face encounter."

READ: Kylie Jenner makes peace with brother, Rob Kardashian

According to the site, Kris "really pissed Rob off" when she chose to go on a tropical vacation with Melanie Griffith rather than celebrating her son's birthday in L.A. last year. Rob's relationship with sister Khloe Kardashian is also not good since she kicked him out of her house when he began dating Blac.

"Things are going really good right now between Rob and Kris and he is not going to let a stupid birthday party mess up all of the progress that he has made with his mother in the past several months," claimed the source.

READ: "I love Blac Chyna" - Rob Kardashian finally tells the world

On Wednesday, March 16, Rob and Blac took to Instagram to share some pictures of them celebrating his birthday with her son at Legoland. "Pre Birthday Turn up," he captioned one of the photos.