These two sing about the sun and stars a lot when professing their love. It's a beautiful image: stars that shine forever, wishing on a star, all that super romantic stuff. But it's also a great way to reference Romeo and Juliet, whom Shakespeare called "star-cross'd lovers," stars in this case being what decided people's fates. Romeo promised to "defy thee stars!" and Juliet at her balcony is actively compared to the sun. If you're going for an adaptation, adapt the best.