I have had quite a few comments on mind so I thought not to waste them on a mere comment.
The story of Luna and her loneliness that led to the creation of Nightmare Moon is quite used and many arts depicted both princess and moon since, in its essence, the moon is connected to feelings of loneliness through many ancient ballads or legends. That, however, does not lessen the impact this particular art nor does it say less of the intended message for several aspects that may or may not have been intended in your art:
1. The mirror like reflection effect below her which gives the viewer the void that one may sometimes feel when one imagines a serene and dark ocean. This particular effect would indeed give a sense of coldness and loss… a certain trait that might indeed have been the catalyst for this character’s change form a regal princess to a tyrant enchantress.
2. The moon and stars: now this thing reminded me of the old legends concerning the wolves’ origins the Indian culture and the tale of the Milky Way Galaxy in the old Chinese stories. A. You see, the old Chinese stories spoke once of a princess and her love who were separated by ungodly force (I am not sure of the exact version since I read about it many years ago) but, through some act of mercy, were allowed to meet and join their hearts in the time of the year when the Milky Way Galaxy would be clear for sight in the sky. This was inspired in me by the light shading given to the night sky in the right left corner and I am aware that it might not be connected to the general idea of your work but the inspiration was given to me none the less. B. As for the wolves legends… well, the stand-alone posture of the princess against the moon reminded me of the Indian legends of the loneliness of the moon: of how it once was a beautiful spirit happy with her lover but a deceitful spirit, driven by jealous, convinced the said lover to fall to Earth to seek the most beautiful of flowers to the lady he loves. Once there, he never returned and the spirit took the form of a wolf and that is why all wolves howl to their lady in the moon.
3. Though the above may indeed not have been intended or might seem quite farfetched and unrelated, the bluish-hue given to the moon does indeed give me the feel of coldness that reminded and me of all that I wrote already. Have you had painted with a yellowish effect, it may not have had the same impact upon me.
4. A perfectly-drawn image would indeed have been a failure: the misty, or hazy, effect given to the drawing of both moon and princess drives one to look closer and closer into it, as if trying to find an error, and that is a capturing trait rarely achieved.