Madeline Bianco

I love this movie. It's a bit confusing but what a love story. The chemistry between Sandra Bullock and Keanu Reeves is phenomenal...something everyone would want to have. I love watching it again and again. I'm trying to find what it was based on. It said at the end of the movie but it's confusing when I look it up . Is it a book? a different movie? What is it based on?