How are assumptions about human relationships challenged in The Crucible?

People in Salem seem to
automatically assume that a good man would never be unfaithful in his marriage, and so it is a
shocking revelation when John Proctor calls Abigail a whore and confesses that he has
"known her" in the court in act 3. For the Puritans, morality seemed to be largely a
black and white issue, and reputation was everything; it must really rock the people in the
courtroom when John makes this confession because Francis Nurse is "horrified"
according to stage direction, and Deputy Governor Danforth is likewise described as
"dumbfounded."

Relationships, even loving partnerships, are not
easy to maintain, and in almost every foundation one can find a crack. People are flawed, and so
our relationships are also. Cheating doesn't necessarily mean there is no love or a lack of
morals. In learning of John's unfaithfulness to his wife, people have to revise their
assumptions about marital relationships.

Further, John believes that his
wife, Elizabeth, would never lie; he says that she is incapable of doing so: "my wife
cannot lie," he says, just as there are those "that cannot sing, and them that cannot
weep." John never thinks for a moment that his wife would lie to protect him, especially
not after his affair with Abigail and the fight between John and Elizabeth in act 2. He makes an
assumption about their relationship, but it turns out that she is willing to
lie for him, to protect his name. His assumption that their relationship is not more important
to her than her moral code is wrong, and he learns how much she really does love him and forgive
him his infidelity, despite her own pain.