A wife can divorce on her own given that she has been  granted the right to Divorce (delegated power of divorce) at the time of the Nikah. This right is given by Husband at the time of Nikah.You are best advised to refer to part 18 of the standard Nikah Nama which is signed in Pakistan.

The right granted under Section 18 of the nikahnama refers to Section 8 of the Muslim Family Laws Ordinance 1961. When invoked, it allows a woman to divorce her husband using Section 7 of the Muslim Family Laws Ordinance 1961, which defines the procedure for talaq (divorce). As a result it allows a woman institute divorce proceedings while retaining her rights over the dower amount, or haq meher, agreed upon by the contracting parties and recorded on the nikahnama.

The clause is of vital significance since a woman who does not have the right of divorce under Section 18 of the nikahnama must resort to pleading for khula (dissolution of marriage), a procedure during which she loses her claim over the dower, alimony or maintenance.

The usual procedure for divorce (as opposed to khula) is that under Section 7 of the Muslim Family Laws Ordinance 1961, the husband presents a notice to the nazim of the relevant union council. If the nazim’s efforts to bring about reconciliation fail, a certificate of divorce is issued within 90 days. Section 8 of the same ordinance dictates an identical procedure for women who have the right of divorce under Section 18 of the nikahnama.