Hindu Marriage Act (25 of 1955) , S.5(ii)(a)(b), S.12(1)(b)— Cancellation of marriage - Ground, that spouse was of unsound mind - Onus of proof lies on heavily on petitioner to establish the case for declaring marriage null and void - Mere fact that spouses had no cohabitation for short period of about a month - Not sufficient to brand wife unfit for marriage and procreation of children on account of mental disorder. S. 5 provides that a marriage may be solemnized between any two Hindus if the conditions specified in the section are fulfilled. Amongst the other conditions stated therein sub-section (ii) it is laid down that at the time of marriage neither party is incapable of giving valid consent to it in consequence of unsoundness of mind or though capable of giving a valid consent, has been suffering from mental disorder of such a kind or to such an extent as to be unfit for marriage and the procreation of children. The clause lays down as one of the conditions for a Hindu marriage that neither party must be suffering from unsoundness of mind, mental disorder, insanity or epilepsy and S. 12(1)(b) refers that any marriage shall be voidable and may be annulled if the marriage is in contravention of the condition specified in Clause (ii) of S. 5. On a plain reading of the said provision it is manifest that the conditions prescribed in that section, if establ....