No idea how old the daughter is .. pretty sure she’s an adult. As I recall, it was claimed he had lunch with her the day of the crime. Still, a LOT of couples stay together even after their last kid has left the home. Of course, this is not your typical couple in any way. And they certainly are not the ‘little people.’
That claim is highly suspect by the authorities as untrue. Though the family may attempt to use this early in the investigation, as they have done, in order to use the courts time later and gain some leverage over the evidence which is so compelling that he did the dead. Last I knew the defense is going to say it was consensual...thus agreeing it happened but blaming the victim...Old story used over ages...some things never change!