The princess must make an important decision that will not only affect her, but the one she loves too. She must decide whether to steer him to death or marriage with another woman.
The king arrests his daughter's lover because he doesn't believe he is good enough for her. The man must pick a door to decide his fate, but either way the king gets rid of him. He'll either get married to a lovely woman, or he'll get mauled by a tiger.
The whole town comes to watch the "King's Arena" where you either see a man get ripped to shreds or a lovely wedding. The accused has more pressure on him with the entire town there watching and waiting to see his fate.