not only do people in abusive relationships often have stockholm syndrome, many people are actually materially dependent on their partner, for example women who have stayed home a long time historically but also still today, and thus they literally cannot leave. Or they have children, or leaving might put others at risk.

Point of working through the analogy being, even on an individual basis framing leaving a relationship as some sort of arbitrary choice is kind of nonsensical, in particular if there is a power imbalance between the people in the relationship, to the point where staying in an abusive relationship might be a 'rational choice'.

Which is actually why we've created very elaborate laws and customs surrounding marriage rather than telling everyone "well if you don't like it just leave".