Their romance is moving at lightning speed!

Scott Disick and his teen girlfriend Sofia Richie flew back from Miami on a private jet yesterday, and the bad boy reality star captioned them "family" as he shared a pic of them eating dinner aboard the plane with pal Jonathan Cheban. A couple things...

First of all, why is Jonathan hanging with them? He's Kim's bestie and a close confidante of Kourtney, so this seems like a MAJOR betrayal. Secondly, does this new couple have something they want to tell us? That "congratulations" cake they kissed over during their trip makes us think they're either engaged or expecting. For those that think it is too soon, just keep in mind Kylie Jenner got pregnant two months into her relationship with Travis Scott!

LD is really pouring on the charm for the 19-year-old.

"Sofia has been interested in him for a long time. She feels like she knows a different side of him and that they are good for each other. She is falling hard and thinks this is the real thing," a source dished to E! News.

"They are inseparable right now and not leaving each other's side. Scott is totally romancing her and she is under his spell. He took her away to Santa Barbara [last] weekend and is spoiling her with shopping trips and sweet gestures," the source added.

We wonder who's paying for the PJ? Our money is on Lionel Richie's daughter!