Why did Medusa get cursed?

In some variations of the myth, Medusa was originally a beautiful young woman who caught the eye of the sea god Poseidon. She was seduced and assaulted by Poseidon in the temple of Athena, who was infuriated by the defilement of her sacred space. As punishment for her role in the sacrilege, Athena turned Medusa into the hideous Gorgon, with snakes for hair and a petrifying gaze.