What is Elizabeth's dilemma when she is brought in for questioning in Act 3 of The Crucible?
Act 3 of the play is a battle for the reasonable folks of Salem to overcome the witchcraft hysteria that has overtaken the town. The act balances on the idea that the court is being used by people like Putnam for self-gain and revenge on their enemies and the idea that witchcraft is real and rampant and only the court can save them.
After much back and forth, Proctor, furious about the sway that Abigail and the other girls have over the court leaders, calls Abigail a whore and confesses to having had sex with her as a way to discredit her. Danforth insists that Elizabeth come in to confirm this story, but he does seem ready to believe it, telling Abigail that if Elizabeth confirms this, God had better have mercy on her (because he won't, presumably).
Elizabeth is brought in, but Proctor and Abigail's backs are to her so they cannot tip her off. Danforth asks her why she dismissed Abigail and she avoids the truth, saying at first that she was dissatisfied with her, then that she was afraid her husband was enamored with her. When Danforth asks if Procter is "a lecher," Elizabeth says no.
Even though Elizabeth chose to lie and protect her husband's reputation rather than remain her completely honest self, her choice ended up doing more harm than good, as Abigail's possession was no longer questioned. Telling the truth here could have ended the trials, but Elizabeth's lie inadvertently kept them going.