I've done it in the past, but I know people who really get off on it. The only reasonable explanation I've heard is the addiction is to endorphins, not the pain. Pain is inherently bad to people, but the cutting isn't bringing mostly pain, it brings a sense of pleasure, a rush.

Self-harm can be dangerous as a coping mechanism. At worst, and statistically unlikely, this is a mock suicide, but Wikipedia ( http://en.wikipedia.org/wiki/Self-harm ) makes me think this is more of a feeling of unreality sort of thing. That's how it was for me. OP, I truly hope your relationship can bring her enough reality, good, strong emotions, as to make the pain unnecessary. I hope this is not a wild dream of mine.