Praise be to Allah.
I put this question to our Shaykh ‘Abd-Allaah ibn ‘Abd al-Rahmaan ibn Jibreen, and he answered as follows:
If a woman dislikes her husband’s treatment of her – for example, he is over-strict, hot-tempered or easily-provoked, or gets angry a lot, or criticizes her and rebukes her for the slightest mistake or shortcoming, then she has the right of khula’ [female-instigated divorce].
If she dislikes his physical appearance because of some deformity or ugliness, or because one of his faculties is missing, she has the right of khula’.
If he is lacking in religious commitment – for example, he doesn’t pray, or neglects to pray in jamaa’ah, or does not fast in Ramadaan without a proper excuse, or he goes to parties where haraam things are done, such as fornication, drinking alcohol and listening to singing and musical instruments, etc. – she has the right of khula’.
If he deprives of her of her rights of spending on her maintenance, clothing and other essential needs, when he is able to provide these things, then she has the right to ask for khula’.
If he does not give her her conjugal rights and thus keep her chaste because he is impotent (i.e. unable to have intercourse), or because he does not like her, or he prefers someone else, or he is unfair in the division of his time [i.e., among co-wives], then she has the right to ask for khula’.
And Allaah knows best.