Complex sentence: One day, the queen was annoyed when another prince refused to marry Turritella, saying that he would gladly marry Fiordelisa, and deciding that Fiordelisa was in league with them, went to visit her tower.
Split into simpler sentences: One day, the queen was annoyed when another prince refused to marry Turritella, saying that he would gladly marry Fiordelisa. The queen decided that Fiordelisa was in league with this prince, and went to visit her tower.