I think it's about how she loves a guy, more than anything, but realizes that they aren't right for each other. Not "the one" as the song says. They are too different to work, so she has to leave him. Also, it might have something to do with his mother, Because she says "I love you like a mother, even after all she's done." The "only sees in black and white" is about how he thinks, something is either one way or the other, and it could be that he sees what his mother tells him. Or maybe I'm reading way too far into these lyrics.
I think it's about how she loves a guy, more than anything, but realizes that they aren't right for each other. Not "the one" as the song says. They are too different to work, so she has to leave him. Also, it might have something to do with his mother, Because she says "I love you like a mother, even after all she's done." The "only sees in black and white" is about how he thinks, something is either one way or the other, and it could be that he sees what his mother tells him. Or maybe I'm reading way too far into these lyrics.