I think the whole song is about a girl who used to have such a romantic view on life, but her view has been changed by bad relationships with bad guys who treated her indecently. I think a the end wen he sings, "I'm miles away from ever understanding/Why I had to be more of a man then," he's looking back and remembering that he treated girls the way this girl that he cares about has been treated--the way he's looking down on other guys for treating girls-- and he doesn't really know why he ever treated anyone that way.
I think the whole song is about a girl who used to have such a romantic view on life, but her view has been changed by bad relationships with bad guys who treated her indecently. I think a the end wen he sings, "I'm miles away from ever understanding/Why I had to be more of a man then," he's looking back and remembering that he treated girls the way this girl that he cares about has been treated--the way he's looking down on other guys for treating girls-- and he doesn't really know why he ever treated anyone that way.