Is it normal that i cant seem to find this situation right?

This was one year ago. I was observing this circumstance where a 16 year old girl was sleeping in the same bed as her father. She didn't live with him but frequently visited him on the weekends and even holidays as he had a restraining order against him and wasn't allowed to associate with his children let alone anyone under the age of 16. Her father you could say was an alcoholic, so obviously when she stayed over she would consume alcohol, sometimes to the point where she would crash out. Here's the concerning sad part though, for years she was abused including sexually, yet she willingly slept in the same bed. you would think anyone that was so messed up and hated their father for this wouldn't even consider sleeping in the same bed just because there was no other beds ( she could have used the couch), anything but that. I'm really wanting to know as it's been on my mind a lot lately, was there something going on and is she mentally ill?