A woman is allowed to ask for divorce for even the smallest reason
1: she is not happy with any particular habit of his even if she doesn’t like him snoring while sleeping, or doesn’t like his smell coming outta her husband’s mouth.
2- she doesn’t get satisfied physically by her husband.
These are just few reasons but Islam gives total flexibility and relaxation to the women in islam.
But at the same time if a wife does SABBAR in those matters Allah S.W.T. will surely reward her with the best not just in this life but in the life hereafter as well.