"The Lady or the Tiger" is a perennial favorite in classrooms across the world. Part of its popularity is because of Stockton's ambiguous ending; even fifty years later each reader can reach a different conclusion as the finish the short story. However, look into the story's themes and you will find timeless themes the continue to confront the modern reader.
The princess could have betrayed her love because she doesn't want to see him with another woman. True, this would have resulted in her lover being killed by the tiger, but do we not continue to see movies where one lover kills another to prevent them from moving on to another? The woman selected to be the bride was described as "one of the fairest and loveliest of the damsels of the court..." perhaps the princess would not want her lover to leave her for such a beautiful woman? Before their affair was discovered, the princess deeply loved the man. It is plausible to believe that she would have been jealous of the courtier.