All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
It is not permissible for a man to dye his hair with black color as clarified in Fataawa 86625, 89129 and 88032. Furthermore, pleasing one’s wife is not a valid justification for violating this rule.
As for women, the Shaafi'ee School of jurisprudence and the scholars who adopt their opinion, are of the view that it is not permissible for her to do so unless she is married and has the permission of her husband.
As a matter of fact, An-Nawawi said: 'It is forbidden for a woman to dye her cheeks or fingers with henna, or to dye her hair with black color, and it is forbidden for her to do so without her husband's permission, but if her husband permits her, it is permissible for her to do so, according to the most correct opinion of the scholars .’
In our view [Islamweb], the most preponderant opinion is that there is no difference between a woman who is married or not married, as the Prophet did not distinguish between them when he said: ''…but avoid black color.''
Allaah Knows best.