According to Ponyboy, why does Cherry not love Dally?

From the text:

As Johnny told him the story, I studied Dally, trying to figure out what there was about this tough-looking hood that a girl like Cherry Valance could love. Towheaded and shifty-eyed, Dally was anything but handsome. Yet in his hard face there was character, pride, and a savage defiance of the world. He could never love Cherry Valance back. It would be a miracle if Dally loved anything. The fight for self-preservation had hardened him beyond caring.