Okay, so Romeo loves Rosaline for her looks, and when he sees Juliet, he calls her a beautiful swan or something like that. He then talks to her, and he realizes he loves her for her personality as well.
As he's figuring all of this out, what my teacher called teenage love dream, Juliet is catching feelings for him as well. He literally plans to run away with her just so they can get married, and then has a secret wedding so they get married. Then he kills himself when he realizes that his love is gone, even though she wasn't gone.
