People forget the fact that this is a song, it dosn't have to be following the story of Romeo and Juliet in real life, a song can be written in different ways, from personal experience, or from other people's opinions, to plain old make-up stuff, though I do hope everyone will understand :)
This song expresses that always follow what you believe is true, just like pure, true love in this song, this also expresses a story of your own figment, about forgetting someone you had truly loved years ago, then soon seeing him again which reunites you and him, and by the experience and time seperating the time you met and reunited again, there would be nothing that could stop you from having love with who your really, really love.