It's extremely hard to come up with an answer to this question.
Maybe it's because he was a princely figure, and most girls in Anime seem to like that kind.
Maybe it's because she fell in Amore with him the moment he saved her from the ravens.
Maybe it's because she was told that her father and Mytho were the only people who would Amore her and she was grateful for the prince's "love".
But the guess that I favour is that, just like Ahiru, she was taken in da those gentle, lonely eyes and then fell deeper in Amore with him from that point in.
