Complex sentence: However, the maiden was a woman that the princess hates, so she must either allow her lover to live and marry another woman, or end his life to prevent him from being with a woman she hates.
Split into simpler sentences: However, the maiden was a woman that the princess hates. The princess then has the decision to either allow her lover to live and marry another woman, or end his life to prevent him from being with a woman she hates.