She wants a divorce but he does not want to divorce her
Question

I have a sister who is married, but her husband has not consummated the marriage with her yet. Everything was fine until my sister suddenly said that she does not want to live with her husband because she no longer loves him. They have not lived together in their house as husband and wife. When her husband heard her say this he got very angry and refused to divorce her. My sister is insisting that she does not want to live with him and he is insisting that he will not divorce her. We have told her that she cannot get divorced without a legitimate shar’i reason and proof, but she says that he gets angry quickly, and discloses secrets. It should be noted that she has not yet lived with him in the same house. Her husband admits that and says that he will change. What is the shar’i solution to this difficult problem?.
Praise be to Allah.If the husband is giving his wife her rights as prescribed in sharee’ah, then it is haraam for her to ask him for a divorce, because the Prophet (peace and blessings of Allah be upon him) said: “Any woman who asked for a divorce for no reason, the fragrance of Paradise is forbidden to her.” Narrated by al-Tirmidhi, 1187; Abu Dawood, 2226; Ibn Maajah, 2055; classed as saheeh by al-Albani in Saheeh Abi Dawood). 
What is meant by the words “for no reason” is without any urgent situation which makes it hard for the marriage to continue.  
If the wife is being harmed and the situation is too difficult for her because of the husband’s falling short in giving her her rights, or his withholding her rights from her, or because of his bad treatment and other similar reasons, then she has the right to ask for divorce, and she may refer to the qaadi and tell him what is happening, and he in turn can ask the husband to give her her rights or to divorce her.  
If she has found out that he has some bad characteristics, he should not hasten to ask for a divorce, rather she has to be kind to him and advise him in the way that is best, and help him to change his character for the better. He acknowledges the way he is and has promised to change. This is a positive step on the husband’s part and it is the first step in dealing with the problem. The wife should help her husband to do good. If every wife wanted a divorce when he was quick to get angry or transmitted some words that were spoken between him and his wife, or other mistakes, there would be no household that was not broken up and its members scattered. 
For more information see the answers to questions no 3758 and  12496. 
And Allah knows best.