Nymph or nymphomania or nympholepsy.
Nymphs are beautiful, idyllic goddesses of wood and stream and nature, often the objects of love and desire. A nymph today may simply mean a remarkably attractive young woman, but if she were to suffer from nymphomania ("nymph-madness"), she would be suffering from sexual promiscuousness. Nympholepsy (from lepsis, "a seizing"), on the other hand, refers to the madness which assails one who has glimpsed a nymph. It can also denote a strong desire for what is unattainable.