Unmarried Woman with Married Man: What is the Sin?

Greetings and blessings

Many serious sins are committed through engaging in relations while single, and the greatest among them is the failure to immerse in the mikvah after menstruation, thus transgressing the prohibition of Niddah, a severe prohibition of karet that both the woman and the man violate each time they engage in relations, in addition to the many other forbidden touches as well.

Even if the young lady immerses in the mikvah, it is still prohibited to engage in relations without kiddushin (formal marriage) and marriage according to the laws of Moses and Israel.

When it comes to a married man, there is an additional severe prohibition, primarily the prohibition of causing harm to another, in which the married woman loses her husband and her interest in him due to the young lady's presence near him—this is of course very palpable to the married woman who suffers greatly from the man’s behavior, with tears on her cheeks, and she has no comforter, may Hashem protect us.

The main way to rectify this is to completely disconnect from the sin and cease all contact with the man entirely. After abandoning the sin, there must be deep and sincere remorse from the depth of her heart for the failure and the mistake, and to accept upon herself for the future to never again be in contact with a stranger man or woman, and to confess before the Creator of the World regarding the mistake and to ask the Creator to place in the heart of the married woman to forgive the girl who has so harmed her through her connection with the husband.

In order to completely cleanse the sin, one must be very careful about observing Shabbat according to its laws and engaging in acts of kindness towards others, such as visiting the sick, helping others, and so forth.

May Hashem assist you in rectifying all imperfections.

Best wishes,

Binyamin Shmueli