When Stockton left the ending of the story ambiguous, he was creating a psychological test that would tell you what kind of person you were based on who you think she chose.
Stockton describes a story where a semi-barbaric king develops a system of justice where the accused has to choose between two doors. Behind one door is a tiger that will maul him to death; behind the other door is a beautiful lady for him to marry. The king has complete faith in his system of justice.
The inevitable happens. The king’s daughter falls in love with a young man, and he does not approve. He sentences the young man to his special arena, and his semi-barbaric daughter finds out what is behind each door. She must choose whether he will die or marry her rival.
Stockton never tells us how the story ends. Which one did she choose? At this point, Stockton directly addresses the reader.
The question of her decision is one not to be lightly considered, and it is not for me to presume to set myself up as the one per-son able to answer it. And so I leave it with all of you: Which came out of the opened door - the lady, or the tiger?
So of course, the reader will wonder. Basically, if you are a cynical person you are going to think that she killed him. If you are a romantic, you will think she let him live.