My girlfriend told me to treat her like a princess.

This joke lands perfectly by playing with two very different definitions of being a "princess." The setup leads us to expect the modern, fairytale version: someone who is pampered, cherished, and treated with romantic adoration. The humor comes from the sudden and absurd pivot to the historical, far more practical definition of the role. The punchline completely subverts our expectations, swapping a romantic comedy for a political drama.

For much of history, being a royal daughter was less about finding Prince Charming and more about being a valuable political asset. Marriages were strategic alliances, designed to secure borders, consolidate power, or end conflicts between rival kingdoms. A princess was often a pawn in a geopolitical chess game. This joke hilariously applies that cold, medieval logic to a modern dating request, creating a fantastic clash between our romantic ideals and a much more cynical reality.