Infidelity is known as Vyabhichara (adultery) in Hinduism. It is a violation of the code of conduct in Hindu married life as prescribed by Dharmashastras. In Hindu religion, chastity is regarded as the most important virtue to be practiced. Cheating in marriage is a grave sin and the person is born in inferior yoni (womb) for next several births and has to suffer.
The wife is expected to serve the husband with great respect. But she also has the freedom to choose another man when her husband is impotent or has cheated on her.
The text on dharma permit a woman to marry another man only under five contingencies – when the former husband is lost, dead, exiled, impotent or fallen from virtue. Otherwise, even the thought of another man as her potential husband or paramour is considered a great sin.
In the same way, a woman courting another for the sake of progeny is censured.
If a man or woman who is not faithful in marriage is condemned for lifetime and is reborn in an inferior state afflicted with disease and sin.
The Hindu Dharmashastras deal with repercussions for disloyalty of husbands and wives.
The texts lay down different types of expiation, such as santapana or chandrayana, for varying degrees of offenses in adultery.
It is also noted that a person associating himself with a sinner becomes impure and has to expiate in the same manner to regain his lost purity.
Some texts on erotica, however, propound that a woman is expiated from the wrong act of committing adultery during her vyabhicharadrtau suddhih (menstruation)
Source –
History of Dharmasastra Vol IV (Third Edition) – 1991 – P.V. Kane – Bhandarkar Oriental Research Institute.
The Encyclopedia of Hinduism Volume XI - (IHRF) (page 458)