The lyrics to the song relate to a woman from Guantánamo, with whom he had a romantic relationship, and who eventually left him. The alleged real story behind these lyrics is that she did not have a romantic interest in him, but merely a platonic one. If the details are to be believed, she had brought him a steak sandwich one day as a present to the radio station where he worked. He stared at some other woman (and attempted to flirt with her) while eating the sandwich, and his friend yanked it out of his hands in disgust, cursed him and left. He never saw her again.
Another history Guantanamera is similar: he was at a street corner with a group of friends and made a courteous pass (a polite pick-up line, like "your mother made you good" or "you came from a star", piropo in Spanish) to a woman (who also happened to be from Guantánamo) who walked by the group. She answered back rather harshly, offended by the pass. Stunned, he could not take his mind off her reaction while his friends made fun of him