Kourtney upset over Scott Disick introducing kids to Sofia Richie

Los Angeles : Reality TV star Kourtney Kardashian is upset over the fact that TV personality Scott Disick introduced their kids to his girlfriend Sofia Richie without giving their mother a head's up first.

On Sunday's episode of "Keeping Up with the Kardashians", the exes got into a bitter argument, reports people.com.

When Kourtney, 39, found out she started crying revealing to sister Kim Kardashian West that she and Disick had been going to therapy together and had agreed to wait before bringing Richie around.

"You know, I think it's just more of a principle thing - that they made this rule and they've been going to this co-parenting therapy together," said Kim, 37.

"I definitely want to be there to support Kourtney and Scott, but it's just kind of their thing and I don't get involved. I kind of agree with Scott on this one but it's Kourtney, she's got to be difficult," added Kim.

Disick, meanwhile, sought advice from Kris Jenner and told her they had agreed to hold off on the introduction until after the holidays.