I can't answer your question about society, but I can venture a guess that William is very secure in his relationship with his younger daughter -- secure enough that he took his girlfriend to Florida with them before Cheryl even went missing. That's pretty ballsy. Since then, they've all vacationed together again just recently. Whatever you picture in your mind how the daughter rationalizes her mom's disappearance, I think the greatest takeaway is that the girlfriend is somewhat of a constant and maybe even a comfort to the daughter.
For family members living outside Cheryl's home, it's got to be torture watching the daughter support Dad, live with Dad, and have a relationship with the girlfriend.
As an aside, it was hard to read your previous post because of the pain I conjured up early in your 2nd paragraph. To be honest, even as a young girl, I've thought one of the most terrifying experiences would be to come across an accident before the first responders arrive. As you approach, you have to brace yourself for what you might see, prepare yourself for what you might have to do or say, and I would imagine fight that "flight" response. You and your neighbors being brave enough to stay there and talk to the victims while waiting for the medics is heroic in itself, because they knew during that time you were talking that they were not alone. That must have been an immense comfort.
