In the Sophocles play Antigone, Antigone and Ismene are in conflict because Antigone wants to defy Creon’s decree to leave Polyneices unburied. Antigone was willing to defy the decree because she felt it was her duty to ensure that Polyneices was shown the proper respect. Ismene, however, refused to taker part in the defiance. She uses several excuses: one, they’re woman, and as such are subject to men’s rule; two, she considers the tragic way her entire family died, and suspects that to defy the king will bring a greater and more tragic death upon them. She also says that she just is not brave enough or strong enough emotionally to defy the king.
Enotes has some great resources.