To me the meaning of this song is a guy loves a girl so much that if she ever killed herself or died that he couldn't live without her because he loves her so much and always will.
This song reminds me of my best friend Keven! I listen to it whenever I'm feeling down or miss him I listen to it and it makes me feel a bit better. I've had a rough go at things right now and I'm glad I have him he's the best friend anyone could ever ask for.
Kevie, if your reading this, I love you so much.