What does this song mean?

Kelsey had some troubles with some guys i the past, but now she's got the singer who loves her and isn't gonna let her go. The singer hasn't been loved by the person who he THOUGHT loved him before, so he can relate to her even more now. NOW, their love is growing stronger and he realizes how much he needs her. This could be one of those situations where Kelsey and the dude were best friends and they dated other people but realized that they were meant for each other.