At the outset I would like to point out that the boy in this case was under the legal age of marriage in India, which is 21 years , thereby making it child marriage. Therefore, Under S. 3(3) of the Prohibition of Child Marriage Act, 2006 the boy has the right to opt out to the marrage until two eyars after attaining majority, i.e 23 years, and ask for an annulment.
On the other hand, grounds for divorce can be identified under the Hindu Marriage Act, 1955, Dissolution of Muslim marriages Act, 1939, Parsi Marriage and Divorce Act, 1936, Indian Divorce Acr, 1869 and the Special Marriage Act, 1956.
If the facts about the marriage could be furnished, I would be able to help in more detail.
Hope this was helpful.