Uh oh ... is there really trouble in paradise?

On Friday afternoon Kourtney Kardashian, who is currently pregnant with her third child with baby daddy Scott Disick, landed at Los Angeles International Airport with daughter Penelope and son Mason -- but Scott was nowhere in sight. While Mason seemed entertained after the 5-hour flight, Kourt and especially little miss P looked a little bit grouchy. What's up with that?

Kourt has reportedly had it with Scott's partying and childish antics, and their relationship drama is on the cover of the latest issue of Us Weekly. Apparently the preggers reality star kicked Lord Disick out of their rented Hamptons mansion on June 9 -- right in the middle of shooting their spin-off show!

"Kourtney was yelling at Scott after she found an inappropriate picture of him with another girl," a source tells the mag. The mother of his children lost her cool in the driveway while cameras were rolling, and Scotty was forced to check into a nearby hotel for the night. Yikes!

"You need to be a more responsible father and get better. There is another baby on the way! You need to straighten up or get out!" she reportedly screamed during the argument. When we polled our X17 readers on Wednesday, we asked if you thought the fight was for real or for ratings, and though 75% of you think it's fake, the rest of you weren't so sure...