It can also be a hostage situation as well. It was named after a case in Stockholm, Sweden where four employees of a bank were held hostage in the bank's vault for six days and developed good relations with the captor and refused to give him away to the cops
So that what it is, a common phenomenon which the victim is emphatic towards abuser, mostly occur within lovers and parents-child.
Learned something new today, ok, another reason to read.