She is asking for separate accommodation; is that regarded as causing separation between her husband and his family?
Question

I married my maternal cousin a month and a half ago, and I do not feel happy with this marriage, because she does not show much respect to me and she goes out of the house a lot to visit her family, and she does not obey me in some matters. One day she said: I want separate accommodation. Please note that I live with my brother and his wife, and my sister, and everyone is happy with us living together and staying as one family. I swore an oath to her that her request would be fulfilled, but she should be patient for a while. But she refused and went to her family’s house. News of that reached my mother and she found out that my wife wants me and my brother to live in separate houses, and she said: If you live with your wife in a separate house I will never enter your house, and neither will your brother or anyone else in your family. Now I am in a bad situation. 1 – Should I disobey my mother and obey my wife, or should I lose my wife and obey my mother? Please note that she did not stipulate in the marriage contract that she should have her house, rather she only stipulated that she should complete her studies. 2 – My family wants me to divorce her and take my money back, because she is being wilfully defiant (naashiz). 3 – My family and my people regard my leaving the house where I live with my brother as something shameful. My question is – is my wife really being wilfully defiant?.
Praise be to Allah.Firstly: 
The relationship between the spouses should be one of love and kindness, especially if they are related to one another, so the rights of kinship are joined with the rights of marriage. Both parties should strive to establish such a relationship. 
Whatever happens of bad treatment between spouses may be due to the husband or the wife, or both of them. Based on that, you should look for the causes of her lack of respect towards you, or her not obeying your commands, and you should strive to sort it out. 
Some woman who are newly married do not understand how important it is to obey the husband, and they do not understand the concept of qiwaamah (being in charge of the family) that is the husband’s role alone. Hence they need some time to understand that, and they may need someone to explain it to them and teach them. Perhaps you could seek the help of some useful tapes and books that speak about the relationship between the spouses and the foundations of its success. 
At the same time, some men go too far in wanting their wives to hear and obey in absolutely everything, and if the wife discusses any issue with him or makes a suggestion or is a little late in doing what he told her to do, he accuses her of nushooz (wilful defiance), disobedience and going against the command of Allah, and not respecting him. 
The husband should never treat his wife as he would treat his servant, and the wife has the right to be respected and consulted, to give her own opinion and to discuss matters so that they will reach the decision that is best. 
Secondly: 
The wife has the right to live in separate accommodation with her husband and children, and not to share it with anyone, whether it is a father, a mother or a relative. 
This is the view of most of the Hanafi, Shaafa’i and Hanbali fuqaha’. She also has the right to refuse to live with his father, mother and siblings. 
Al-Kaasaani said in Badaa’i al-Sanaa’i (4/24): If the husband wants to make her live with her co-wife or in-laws, such as the husband’s mother or sister or daughter from another wife or his relatives, and she refuses to do so, then he has to accommodate her in a separate house, because they may annoy her or harm her if they live together, and her refusal is an indication that she is being bothered or harmed. And because he needs to be able to have intercourse with her or be intimate with her at any time, and that cannot be done if there is a third person living with them. End quote. 
Shaykh al-Islam Ibn Taymiyah favoured the view that if the husband is poor or unable to provide separate accommodation for his wife, she does not have the right to ask for something he is unable to give. This was narrated from him in Mataalib Ooli al-Nuha (5/122). Rather she should bear it with patience until Allah gives him the means.  
To sum up, separate accommodation is the wife’s right, even if she did not stipulate it in the marriage contract, and she has the right to ask for it now, and she is not regarded as being wilfully defiant because of that. The commonly held view among some people, that this is creating division among siblings, is not true, because this is a shar’i right of the wife, and it serves the interests of both spouses, because it prevents free mixing and guards them against looking at things that are not permissible. It is unfortunate that in many shared family homes, a man may look at his brother’s wife, and they may shake hands or be alone together, which may lead to jealousy, envy, disputes and separation. There may also be arguments because of the children. Undoubtedly a man is a stranger (non-mahram) to his brother’s wife, so it is not permissible for him to shake hands with her or be alone with her or look at her, unless he is a mahram to her through some other means, such as breastfeeding. 
The one who looks at shared family homes will be certain of the wisdom of what the scholars have said, that a wife should have her own home, because in many of these homes there are problems and differences between the spouses and between a man and his brother, and between the wife and her husband’s mother, and so on, as well as the many evils and things that go against Islam. 
Finally, what we advise you to do is to strive to bring about a reconciliation between your wife and your mother and family, and give each one his or her dues. Give your wife her right to separate accommodation, and it will not matter if any of them get angry about you having your own home, because you are not doing anything wrong. But you have to continue to uphold ties of kinship with your relatives, mother and brothers. 
If you cannot afford to provide a separate home for your wife at present, then you can make her a promise and advise her to be patient until Allah makes you independent of means by His bounty. 
I ask Allah, may He be exalted, to reconcile between you and unite you, and to increase the love and affection between you. 
And Allah knows best.