1. If the husband is not spending the amount of money required of him to provide her and and her dependents food and shelter; if he has ceased cohabiting with her, whether deliberately or for a protracted period (i.e. one year or more), due to absence abroad, imprisonment, or sickness for example (but not due to study, trade, lawful employment, or military service) or even under one and the same roof for a period varying from six months to three years according to the jurists of the different schools; if she has discovered a physical or other blemish in him that makes the conditions of conjugal life impossible or intolerable, such as sexual impotence or insanity (in which cases the marriage may already be invalid to start with, since the absence of such defects is a precondition for its validity); if any of the explicit additional conditions agreed upon in the marriage contract (if any) is not met; if he mistreats her in a patently cruel and unbearable way (e.g. she bears the marks of beating on her face or body), if he is or becomes a non-Muslim or prevents her from praying then there is grounds for divorce.
2. She should first ask her husband to give her a divorce after duly ascertaining that one of the above conditions is present, as shown by the hadith: "Any woman that asks her husband for a divorce without actual harm [being committed against her], then forbidden to her is the scent of Paradise." Thereafter, ask a knowledgeable and Godfearing qadi or imam to grant it. She should see the qadi or imam, preferably together with her husband. The spouses must be prepared to receive and apply matrimonial counsel and must show that all avenues of reconciliation have been exhausted. At any rate, the qadi or imam has to verify, after due course of investigation and cross-examination, that the wife is being mistreated in a harsh and intolerable manner before he can pronounce a divorce. The wife must also be prepared to spend her `idda (post-separation waiting-period of four months and ten days) under the conjugal roof during which time cohabitation is forbidden. And Allah knows best.
I also found the following material I had saved from previous discussions on the issue:
Family Law in Pakistan is in adherance with the principles of the Hanafi madhhab.
The Dissolution of Marriages Act of 1939 in Pakistan provides the woman the facility of obtaining what is called "judicial divorce" by decree of a court. Section 2 of this Act paraphrased below stipulates the grounds whereby this dissolution of marriage can be sought by the woman:
1. husband's whereabouts unknown for 2 years
2. husband's full delinquency in providing maintenance for 2 years
2a. husband's polygamy on an illegal basis
3. husband's imprisonment for 7 or more years
4. husband's delinquency in performing marital obligations for 3 years
5. husband's impotence at time of marriage and up to application
6. husband's insanity for 2 years, leprosy, or virulent venereal disease
7. wife having been given in marriage before 16 years of age and repudiating the marriage before 18, provided marriage was not consummated
8. husband's cruelty such as:
a. habitual assault or even non-physical ill-treatment
b. associating with prostitutes or leading an infamous life
c. attempting to force her into prostitution
d. disposing of her property or preventing her rights over it
e. obstructing observance of her religious duties
f. not treating her equitably according to Qur'an if he has more than one wife
Source: Muhammad Sharif Chaudhry, "Women's Rights in Islam" (Lahore: Ashraf, 1991), p. 60-61.
And may Allah's blessings and peace be upon Muhammad,
his Family and all his Companions,
and praise be to Allah, Lord of the worlds.