Yeah, probably this is a sad song, but I don't wanna see it like that.
This is a story about two people. He has hurt her by being "the worse side" of her and being the villain in their relationship (for example he didin't give enough time for her and her needs and he didn't seem to care enough; it doesn't necessarily mean he did something, I think it's about he didn't do something). So, the girl got fed up, decided that he wasn't what she needed, but now when she has made him just another friend of hers he realizes he wants her back. "This silver leaves me longing for gold"; he doesn't want just stay watching her and spendin' good time with her, he wants their former relationship back and he hopes she can give him another shot. He sings "I'm miserable without you you know" and "I'm never been the kind to let go", so he can't move on without her by his side. He knows that he's not perfect, he knows he's the worse of them two, but still he is trying to fix things by this song.