The only theory I can come up with is that Cheryl wasn't the one driving her car that morning. Video at her home shows her car leaving, video later shows her car going towards the transit area, BUT, thus far no a single witness has come forth saying they SAW or SPOKE to Cheryl that morning, nor that weekend! To me, that is important!
If someone saw Cheryl pull over, get out of her vehicle, or saw her pulled over texting the friend, they haven't announced it.
While I don't know WHO harmed Cheryl, I don't think it was herself! Anyone could have been driving her car, hopped on the bus, and went about their business.
Not going to get into whether her husband knew who was driving or not. I have nothing to say either way.
Find me a witness outside the home that saw her, talked to her that weekend, and especially that morning. Until then, Cheryl wasn't driving, IMO.