He realized that the family had a separate baby shower for Chyna after he struck out at his family without talking to them first.
"It was miscommunication on my end," Rob Kardashian said Friday on On Air With Ryan Seacrest.
"I thought they weren't having Chyna at our baby shower. Chyna's baby shower is actually this Sunday, but they were trying to do a little surprise 'guy' baby shower for me and I was just upset trying to fight for Chyna like, 'Yo, she has to be at the baby shower. She's birthing my child. She needs to be there.' It was literally miscommunication and I probably shouldn't have went on Twitter, but I did."
"I kind of took all my anger out on Kylie and my family. It wasn't just Kylie, it was my whole family. I went in on them on group text. And I was just being petty and posted Kylie's number.
I was like, 'Yo, it's not that serious. We change our numbers all the time."
"We all love each other and we're all family and I never want to beef or argue with anybody," he said.
He said what his family does is never just for the cameras. These are "all real issues that are actually happening. It's so many siblings that it's hard to communicate with everybody, honestly."
Then he apologized his sister on air saying:
"I'm sorry, Kylie, if you're listening". "I love you, Kylie."