The question outsiders always ask about an abusive relationship — "why don't they just leave?" — has a behavioral answer with fifty years of research behind it, and the answer starts with pigeons.
B.F. Skinner and Charles Ferster catalogued reinforcement schedules in 1957 and documented a result that still runs the casino industry: rewards delivered unpredictably produce more persistent behavior than rewards delivered every time. A pigeon fed on every peck quits pecking soon after the food stops. A pigeon fed on a random schedule keeps pecking long after the feeder goes dead, because "no reward yet" and "reward coming" look identical from inside. Slot machines pay on exactly this schedule. So, it turns out, does a certain kind of partner.
Psychologists Don Dutton and Susan Painter proposed traumatic bonding theory in 1981 to explain the attachment battered women reported toward their abusers. They pointed to two structural features, not to any weakness in the victim:
Sit with that finding, because it's the counterintuitive core: the relationship where the kindness comes unpredictably binds tighter than the relationship that is uniformly bad. Uniform cruelty lets the pigeon stop pecking. The good week after the terrible month is what keeps the lever warm. Survivors who describe leaving as physical withdrawal are describing the mechanism accurately.
If this post reads like your current relationship rather than an interesting mechanism, the right next step is a human: a therapist who knows trauma, or the National DV Hotline. Drills help people spot the schedule early — before the bond sets. Once it's set, unwinding it is clinical work, and pretending otherwise would be its own manipulation.
For spotting it early: the intermittency pattern is drilled in the Companion world, where the warm-cold cycle runs in compressed time and gets named on every swing.