This makes sense, considering our evolutionary heritage.
Our brains are crazy interconnected masses of gelatinous goop. I'd highly suspect that there is more overlap between different mental functions than we realize. I doubt there is a strict divide between physical and emotional pain, just as I distrust the separation of logic from emotion, or any other interrelated abstract system.
Our brains are delicate places, and the troubadours have known all along that heartache feels like being punched in the gut.