In Miller's play "The Crucible," John Proctor finds it difficult to admit his adulterous relationship with Abigail Williams. The reasons why can be justified by individual readers by using Reader-Response theory.
Reader-Response theory examines a text from the reader's point-of-view. The intent of the author is basically negated.
Therefore, the reason he wishes to keep the affair secret can be for any of the following reasons.
1. John Proctor wishes to keep his wife's name, Elizabeth Proctor, and her status good. He does not want anyone knowing about the affair because it could tarnish Elizabeth's name.
2. John Proctor does not wish to harm his integrity as a man of the community. If people knew about his affair with Abigail, they would speak harshly about him.
3. John only tells the truth about his relationship in order to show Abigail's falsely pointed accusations. While he does not want his wife to be accused of witchcraft (where he would keep the truth of the affair hidden), he decides to admit to the truth so as to show Abigail as she truly is.
John Proctor is not unlike many people today. He is shamed by the fact that he had the affair and does not wish to have anyone know the truth. He told Elizabeth, she fired Abigail because of it, and for him (being a private man) that should have been enough.