So he didn't tell NK (about needing the babysitter, not being able to spend the night with her) Wednesday night, Thursday, Friday, Saturday, until sometime after 5:30 when their date started.
Re the airport, in one of those interviews, IIRC the one in the parking lot/Firestick, it was mentioned that CW had the day off to take SW to the airport.
I wonder what vehicle he used to visit NK Wednesday night, remember he had told his boss that the GPS on his truck might show up at other addresses because of all the marital stress in his life, so he had that one covered
.
So, he was busy balancing lies to everyone, even his employer, as the self-created pressure built. Avoiding telling the mistress, hey I just can't really ever get away anymore, telling SW they were going to have a romantic getaway.
NK was a lot more volatile than we had known before he told Lee/Coder the ledge bit, she went off over the smallest things. She, IMO, clearly read him the riot act Saturday night and then continuously for 111 minutes right before he murdered them.
He apparently didn't have enough gumption to hang up.