Mary Navas I had forgotten the fantasy until Zachary recalled it, but I think you've got the characters reversed. It's Cheryl running towards him. She is the same, engaged and loving actively, while Clee is passive.
Zachary It's the scene Cheryl was imagining earlier in the book where she meets a grown-up Jack at the the airport, only this time its actually happening. Jack is returning from China with a woman, presumably his girlfriend, and she is asking him about Cheryl and what she should call her. (Not "Mom" apparently.) Jack is surprised to see that Clee has come too, but not enough to suggest he never sees her, just surprised that she showed up to meet him. Cheryl waits for him and Clee runs to meet him, showing that they are fundamentally the same people that we meet at the book beginning of the book. One passive, one aggressive.
Ewan I read it as being ambiguous as to whether it was real or another of Cheryl's fantasies. Perhaps it is real, but on the other hand, it's basically an updating of the fantasy Cheryl had earlier on, but with certain details updated. The presence of Clee suggests to me that it's wishful thinking that they've gotten back together, but I think the whole point is for you to consider whether it's real or imaginary.