Ok, this song has many different reasons and you can believe what you think this song means but this is what I think this song means.
Our relationship is like a roller coaster, we have days that go up and down. But when we brake up my life is like hell and I don't think there is anyone in the world like you, just for me. And that I will love you for ever and I hope you think the same for me, till we die.
^_^
P. S. This song is a cool and could have 1 in 100 or more, other meanings.