Complex sentence: Pandora, deeply saddened by what she had done, feared she would have to face Zeus' wrath, since she had failed her duty; however, Zeus did not punish Pandora, because he knew this would happen.
Split into simpler sentences: Pandora, deeply saddened by what she had done, feared she would have to face Zeus' wrath, since she had failed her duty. However, Zeus did not punish Pandora because he knew this would happen.