Ignoring warnings that she was damaging a 14th century UNESCO World Heritage Site, the tourist persevered with the engraving until she was finished.
She chose one of the most precious sites at the Alhambra: the richly decorated Comares Palace, the official residence of the Nasrid rulers of the Moorish Emirate of Granada.
Private security guards at the Alhambra called Spanish national police when the woman failed to heed their warnings. Police then arrested the woman, accusing her of committing an offence against the nation's cultural heritage.
"She did not resist arrest," a Granada national police spokesman told The Local.
"She wrote two letters on the side of what appeared to be a heart. The initials did not correspond with her own."
Police said the woman was born in Switzerland in August 1993 and lives in Pfäffikon. Her last name indicates she is of Arab origin. She was arrested at 5.30pm on Saturday.
She spent the night of January 7th in prison and was brought before a court the next morning, where she refused to testify. She is now awaiting trial.
Police said the site she chose for her amorous engraving, rather than the specific damage done to the building, made her crime much more serious than a regular graffiti case.
Granada district court will decide whether to fine her or hand down a custodial sentence.
"The damage is superficial, but we can't allow this kind of behaviour to take place," a spokeswoman for the Council of the Alhambra told The Local.
"These kinds of offences fall under the National Heritage Law. It's like damaging a painting at the El Prado museum."
Police and the Alhambra council said crimes of this nature were rare at the historical site.
"We only made one other arrest in the whole of last year, when a Jordanian citizen was arrested for scratching the walls with a coin," said the police spokesman.
He was fined €320.