edit: please read the second part if my post too.
I binged it yesterday and I think I sort of can understand/explain why Caroline kept returning to him. It's not all black and white, she was unstable, was not getting any help etc.
On top of that I don't really understand her parents, like to me it was a lack of support from them. She was in her apartment with the brothers - they didn't help. They didn't go with her to court to support her. And a few more qns.
So my understanding was she only stayed with Sandy because she thought it was the safest option not blow her cover as a witness.
But I am reading an article about all this in Times and it seems Netflix brought slightly different story? And reality does explain why Caroline stayed with him and why parents were not able to do much?
She HAD to stay with the brothers to get more evidence and the police DIDN'T LET HER have any support because it could compromise the case.
Here:
She underwent a nine-month undercover stint to help police gather more evidence against the McKellars. She told the Daily Record that she was close to an emotional breakdown and that her mental health made her unable to work. “From the word ‘go’ the police, they were saying if I didn’t cooperate with them I could end up in trouble myself," she said. “I put so much trust in them and they promised anonymity, support, yet the minute you give them what they want you’re hung out to dry. They suggested from the start that I could also end up in trouble with assisting a criminal, wasting police time, aiding and abetting."
“They never said ‘you must record,’ but it was heavily insinuated that the first one was so helpful,” Muirhead says of her decision to provide evidence for the murder trial. “And they’d say, ‘You must have more information, they must be talking about it. You’re with them all the time.’ The police were doing surveillance on them the whole time. I didn’t have any mental health support; they said I wasn’t allowed any because it could compromise the case.”