Section 13 in The Hindu Marriage Act, 1955

13 Divorce. —
(1) Any marriage solemnised, 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—
16 [(i) has, after the solemnisation of the marriage, had voluntary sexual intercourse with any person other than his or her spouse; or]
16 [(ia) has, after the solemnisation of the marriage, treated the petitioner with cruelty; or]
16 [(ib) has deserted the petitioner for a continuous period of not less than two years immediately preceding the presentation of the petition; or]
(ii) has ceased to be a Hindu by conversion to another religion; or
17 [(iii) has been incurably of unsound mind, or has been suffering continuously or intermittently from mental disorder of such a kind and to such an extent that the petitioner cannot reasonably be expected to live with the respondent.
Explanation .—In this clause,—
(a) the expression “mental disorder” means mental illness, arrested or incomplete development of mind, psychopathic disorder or any other disorder or disability of mind and includes schizophrenia;
(b) the expression “psychopathic disorder” means a persistent disorder or disability of mind (whether or not including sub-normality of intelligence) which results in abnormally aggressive or seriously irresponsible conduct on the part of the other party, and whether or not it requires or is susceptible to medical treatment; or]
(iv) has 18 [***] been suffering from a virulent and incurable form of leprosy; or
(v) has 18 [***] been suffering from venereal disease in a communicable form; or
(vi) has renounced the world by entering any religious order; or
(vi) has not been heard of as being alive for a period of seven years or more by those persons who would naturally have heard of it, had that party been alive; 19 [***] 20 [ Explanation. —In this sub-section, the expression “desertion” means the desertion of the petitioner by the other party to the marriage without reasonable cause and without the consent or against the wish of such party, and includes the wilful neglect of the petitioner by the other party to the marriage, and its grammatical variations and cognate expressions shall be construed accordingly.] 21 [***]
22 [(1A) Either party to a marriage, whether solemnised before or after the commencement of this Act, may also present a petition for the dissolution of the marriage by a decree of divorce on the ground—
(i) that there has been no resumption of cohabitation as between the parties to the marriage for a period of 22 [one year] or upwards after the passing of a decree for judicial separation in a proceeding to which they were parties; or
(ii) that there has been no restitution of conjugal rights as between the parties to the marriage for a period of 22 [one year] or upwards after the passing of a decree for restitution of conjugal rights in a proceeding to which they were parties.]
(2) A wife may also present a petition for the dissolution of her marriage by a decree of divorce on the ground,—
(i) in the case of any marriage solemnised before the commencement of this Act, that the husband had married again before such commencement or that any other wife of the husband married before such commencement was alive at the time of the solemnisation of the marriage of the petitioner: Provided that in either case the other wife is alive at the time of the presentation of the petition; or
(ii) that the husband has, since the solemnisation of the marriage, been guilty of rape, sodomy or 23 [bestiality; or]
24 [(iii) that in a suit under section 18 of the Hindu Adoptions and Maintenance Act, 1956 (78 of 1956), or in a proceeding under section 125 of the Code of Criminal Procedure, 1973 (2 of 1974) [or under the corresponding section 488 of the Code of Criminal Procedure, 1898 (5 of 1898)], a decree or order, as the case may be, has been passed against the husband awarding maintenance to the wife notwithstanding that she was living apart and that since the passing of such decree or order, cohabitation between the parties has not been resumed for one year or upwards; or
25 [(iv) that her marriage (whether consummated or not) was solemnised before she attained the age of fifteen years and she has repudiated the marriage after attaining that age but before attaining the age of eighteen years.]
Explanation. —This clause applies whether the marriage was solemnised before or after the commencement of the Marriage Laws (Amendment) Act, 1976 (68 of 1976)*.] State Amendment Uttar Pradesh: In its application to Hindus domiciled in Uttar Pradesh and also when either party to the marriage was not at the time of marriage a Hindu domiciled in Uttar Pradesh, in section 13—
(i) in sub-section (1), after clause (i) insert (and shall be deemed always to have been inserted) the following clause, namely:— “(1a) has persistently or repeatedly treated the petitioner with such cruelty as to cause a reasonable apprehension in the mind of the petitioner that it will be harmful or injurious for the petitioner to live with the other party; or”, and “(viii) has not resumed cohabitation after the passing of a decree for judicial separation against that party and—
(a) a period of two years has elapsed since the passing of such decree, or
(b) the case is one of exceptional hardship to the petitioner or of exceptional depravity on the part of other party; or
(ii) for clause (viii) (since repealed in the principal Act) substitute (and shall be deemed to have been substituted) following clause, namely:—
[ Vide Uttar Pradesh Act 13 of 1962, sec. 2 (w.e.f. 7-11-1962)].
(i) Cruelty which is a ground for dissolution of marriage may be defined as wilful and unjustifiable conduct of such character as to cause danger to life, limb or health, bodily or mental, or as to give rise to a reasonable apprehension of such a danger. The question of mental cruelty has to be considered in the light of the norms of marital ties of the particular society, to which the parties belong, their social values, status, environment in which they live. Cruelty need not be physical. If from the conduct of the spouse it is established or an inference can be legitimately drawn that the treatment of the spouse is such that it causes apprehension in the mind of the other spouse, about his or her mental welfare then this conduct amounts to cruelty; Maya Devi v. Jagdish Prasad, AIR 2007 SC 1426.
(ii) Making false allegations against husband of having illicit relationship and extramarital affairs by wife in her written statement constitute mental cruelty of such nature that husband cannot be reasonably asked to live with wife. Husband is entitled to decree of divorce; Sadhana Srivastava v. Arvind Kumar Srivastava, AIR 2006 All 7.
(iii) The expression “Cruelty” as envisaged under section 13 of the Act clearly admits in its ambit and scope such acts which may even cause mental agony to aggrieved party. Intention to be cruel is not an essential element of cruelty as envisaged under section 13 (1) (ia) of the Act. It is sufficient that if the cruelty is of such type that it becomes impossible for spouses to live together; Neelu Kohli v. Naveen Kohli, AIR 2004 All 1.
(iv) The levelling of false allegation by one spouse about the other having alleged illicit relations with different persons outside wedlock amounted to mental cruelty; Jai Dayal v. Shakuntala Devi, AIR 2004 Del 39.
(v) Mental disorder for relief under section 13 (1) (iii) should be of such a degree that it is impossible to lead normal marital life or it is unreasonable to expect a person to put up with a spouse with such condition; B.N. Panduranga Shet v. S.N. Vijayalaxmi, AIR 2003 Karn 357
(vi) Due to the criminal complaint filed by the wife, the husband remained in jail for 63 days and also his father and brother for 20 to 25 days. Therefore, even though the case of cruelty may not have been proved but as the facts emerging from the record clearly indicate that the living of the two as husband and wife would not only be difficult but impossible, the court has no alternative but to grant a decree of divorce; Poonam Gupta v. Ghanshyam Gupta, AIR 2003 All 51.
(vii) Unless the entire genesis of the quarrels in the course of which, one of the spouses holds out a threat to take his or her life is placed before the court, the very fact that some threat in the course of a quarrel is held out, cannot be viewed in isolation or construed as mental cruelty to the other spouse; Nalini Sunder v. G.V. Sundar, AIR 2003 Kar 86.
(viii) A husband cannot ask his wife that he does not like her company, but she can or should stay with other members of the family in matrimonial home. Such an attitude is cruelty in itself on the part of the husband; Yudhishter Singh v. Sarita, AIR 2002 Raj 382.
(ix) Removal of mangalsutra by wife at the instance of her husband does not amount to mental cruelty; S. Hanumantha Rao v. S. Ramani, AIR 1999 SC 1318.
(x) A threat to commit suicide by the wife amounts to infliction of mental cruelty on the husband but it should not be uttered in a domestic tiff; Pushpa Rani v. Vijay Pal Singh, AIR 1994 All 220.
(xi) Solitary instance of cruelty would not constitute cruelty so as to grant a decree for divorce rather the behaviour of the other party has to be persistently and repeatedly treating the other spouse with such cruelty so as to cause a reasonable apprehension in the mind of the husband/wife that it will be harmful or injurious for him or her to live with the other party. The expression “persistently” means continue firmly or obstinately and the expression “repeatedly” means to say or do over again; Vimlesh v. Prakash Chand Sharma, AIR 1992 All 261.