Our Gemara and Mishna on Amud Aleph discusses certain breaches in the marriage that forfeits the woman’s right to her kesuba.  One of these breaches are if the woman falsely pretended to not be a niddah, when in fact she was, leading to them having relations during a forbidden time.

This phenomenon happens more often than people would like to believe.  I have no statistics, but having the privilege of working with couples for 28 years, I do get to hear and see a lot. Men and women have different tendencies and emotional defenses.  Often, when men are frustrated, they turn to aggression.  When women are frustrated, they may turn to more passive forms of aggression.  This is not always true, rather it is a pattern of masculine and feminine behavior.  Thus, if a woman feels angry or trapped, she is less likely to respond with aggression and more likely to take covert action such as lying.  It is in fact described thusly within the Torah with both Sarah outright opting out of fear (Bereishis 18:15), and Rivka engaging in subterfuge and manipulation of Yitschok in pursuit of obtaining a blessing for Yaakov (see beginning of Bereishis 27), as well as hiding the real reason that Yaakov had to run away (Esau’s murderous rage) by making it about Shidduchim (End of Bereishis 27 and beginning of 28).

The Gemara (Gittin 6b) warns:

אָמַר רַב יְהוּדָה אָמַר רַב כׇּל הַמֵּטִיל אֵימָה יְתֵירָה בְּתוֹךְ בֵּיתוֹ סוֹף הוּא בָּא לִידֵי שָׁלֹשׁ עֲבֵירוֹת גִּילּוּי עֲרָיוֹת וּשְׁפִיכוּת דָּמִים וְחִילּוּל שַׁבָּת

Rav Yehuda says that Rav says: Anyone who imposes excessive fear upon the members of his household will ultimately come to commit three sins: Engaging in forbidden sexual intercourse, as the wife will be so fearful of her husband that she will sometimes tell him that she has immersed in a ritual bath after her menstruation has ended when she has not done so (see Rashi); and he will also end up committing bloodshed, as she is likely to run away from him and expose herself to dangers; and desecration of Shabbat, as she will cook for him on Shabbat because she is scared that he will be angry with her for neglecting to do so beforehand.

I therefore strongly advise husbands to never, ever get annoyed when your wife suddenly becomes a niddah, asks extra sha’alos, or perhaps even makes it difficult by checking when she is not supposed to.  Your anger and annoyance can lead to intimidation, and God forbid, deception about this serious matter.  Always honor mikvah night and the process, making sure your wife has the time, respect, and support to make preparations and go to a Mikvah that feels comfortable.  These steps are an excellent preventative so that no one should be tempted to disregard or take shortcuts in one of the most important mitzvos.