Adultery is one of the grounds for divorce as per the Hindu Marriage Act 1955. Section 13(1)(i) of the Act states that any marriage solemnized, whether before or after the commencement of this Act, may, on a petition presented by either the husband or the wife, be dissolved by a decree of divorce on the ground that the other party has, after the solemnization of the marriage, had voluntary sexual intercourse with any person other than his or her spouse.

However, it’s important to note that the act of adultery must be proved by the petitioner and the court must be satisfied that the other party has indeed committed the act. In case of evidence provided is not sufficient, the court may dismiss the petition.

In the case of Sowmithri Vishnu v. Union of India (1985) 3 SCC 618, the Supreme Court held that the act of adultery is not a criminal offense but it is a ground for divorce. The court also laid down the standard of proof required for adultery, stating that the evidence must be clear, cogent, and convincing and that the court must be satisfied that the other party has indeed committed the act.

In the case of Joseph Shine v. Union of India (2018) 10 SCC 1, the Supreme Court held that the Section 497 of Indian Penal Code (IPC) which criminalized Adultery is unconstitutional. The court held that the section is violative of Article 14 and 15 of the Constitution of India and it is discriminatory against women. The court also held that Adultery can be a ground for divorce but it can’t be a criminal offense.

It is important to note that the court may take a lenient view if the act of adultery is condoned by the other party or if it was committed due to the conduct of the other party. In such cases, the court may dismiss the petition for divorce.

It’s also worth noting that the concept of adultery is different than that of the cruelty in marriage, and it is the burden of the petitioner to prove the act of adultery rather than the burden of the respondent to prove the absence of it.