 He keeps her a swan by day so that no one will fall in love with her, as the only way Rothbart's power can be defeated is when a man loves her with all his heart and soul.Siegfried explains that he already felt something for her the moment he saw her eyes, and asks her to go to his birthday ball the next night, where he will choose her as his bride.Although at first she refuses, Siegfried is intent and won't take no for an answer, convinces her and when she returns to her room she daydreams of him.