Who is Lucy from The Sun, the Moon, the Stars and what is their importance?

Lucy meets Yunior at the resort in La Romana. She has returned to the Dominican Republic for a vacation, as she now lives in New York. Physically, she resembles Magda with her dark curly hair and light complexion. Lucy is beautiful, but her beauty is often flawed. In this respect, she represents the Dominican Republic symbolically. Yunior finds Lucy's beauty tempting, but he resists.