Under the Hindu Marriage Act, 1955, a wife can seek divorce if the husband had another wife:

Section 13(2)(i) covers pre-Act marriages where "the husband had married again before such commencement" or another pre-Act wife was alive when the petitioner married, "Provided that in either case the other wife is alive at the time of the presentation of the petition". A second marriage after the Act is void under section 11 read with section 5(i).