When one of the parties is not consenting to the divorce, the only option left is to fight for divorce in a court of law, such a divorce is called contested divorce. So your friend can approach the respective Family Court and file a petition for a decree of divorce.
Section 13 of the Hindu Marriage 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 -
1. After the solemnization of the marriage, had s*xual intercourse with any person other than his or her spouse,
2. After the marriage has treated the partner with cruelty
3. Deserted the partner for a period of not less than two years or has been absent for a period of 7 years without the knowledge of being alive
4. Ceased to be Hindu by conversion to some other religion,
5. been incurable of unsound mind or has been suffering continuously from a mental disorder.
To obtain a decree of divorce, your friend can approach a good divorce lawyer and file a petition. But it is recommended that she should try mediation first and see arriving at a peaceful settlement might be possible.
I hope this helps!