In the lyric, the singer also feels tortured. She is very confused. She does not know what to do. Of course it's impossible his boy instantly appears in front of her since in fact he is far away. Hence she sings' "what I'd do to have you." This line reflects the feeling of despair and expectation at the same time. You expect something to happen, but you know that it's impossible to happen. It's understandable then if Avril curses 'damn, damn, damn' in the chorus of the song. Well, If you are in despair, and you are very confused, but you expect something to happen, what else you can do but cursing. So let me also curse, Damn the song is so good :D.