Some sort of voluntary ness is involved. They are not cutting the throat of their 'husband' while he sleeps, they are not poisoning the kids to spite him, they aren't taking the first opportunity to slip away into the jungle, etc. The more days that pass, the more opportunities they are passing up. Hence, Stockholm syndrome. People can get used to pretty much anything.

Someone in a supermax can be truly involuntary: burly men at every point stand ready to force them to do something, will force them into the solitary cell, will force-feed them food if they go on a hunger strike, will call for doctors and powerful sedatives, and hard concrete and steel hem them in.