Problems caused by wife’s illness
Question

                My brother married a woman who suffers from retinal atrophy, and he did not know anything about her sickness until two months ago. All he knew was that her vision was weak, and he got married to her. Now he is wondering whether he should separate from her because he feels that she will not be able to raise his children properly if she has children.

 He is always arguing with her mother because she speaks badly to him and he thinks that she bewitched him to make him marry her daughter. Now he cannot control his anger most of the time and he beats his wife, and he insults her in horrible terms. I hope you can suggest what is best for them.
Praise be to Allah.
    What you have mentioned about her suffering from retinal 
    atrophy is not one of the faults which the fuqaha’ have stated give the 
    husband the choice of annulling the marriage. But some scholars, such as 
    Shaykh al-Islam Ibn Taymiyah, and Ibn al-Qayyim – and Shaykh Ibn ‘Uthaymeen 
    who regarded it as being the correct view – narrated that every fault which 
    puts the other spouse off, so that the purposes of marriage, namely 
    compassion and love, cannot be achieved, mean that the spouse has the choice 
    of annulling the marriage. (Zaad al-Ma’aad, 5/163) 

    Based on this, the choice of annulment is given in every case 
    where there is a fault that affects the purposes of marriage, namely love, 
    intimacy, bearing children, etc. 

    But your brother came to know of this fault after that, and 
    he did things which indicate that he accepted that, namely continuing to be 
    intimate with her and not hastening to annul the marriage. According to the 
    fuqaha’ this indicates that he accepts it, and that he does not have the 
    right to annul the marriage. 

    But as you know, divorce is the man’s right and he may 
    divorce his wife if he thinks that he cannot live a good life with her and 
    that he cannot feel love for her and feel at ease with her, which is the 
    basis of marriage. 

    What we advise in such situations is to be patient with this 
    wife and try to solve the problem. If her mother is the main reason for the 
    problems, then it is better to keep a distance from her and to live in 
    separate accommodation. If your brother lives in the same house as her or 
    nearby, then it is sufficient to keep in touch by phone and pay brief 
    visits, etc. If the wife’s bad attitude is the reason for the problem, then 
    your brother should check himself and how he treats his wife, for the way he 
    treats her, beating her and calling her names, may be the reason for her bad 
    attitude. He should seek the help of people who have experience in dealing 
    with such problems, and try different ways of finding a solution to each 
    problem. 

    Allaah says (interpretation of the meaning): 
“If you dislike them, it 
    may be that you dislike a thing and Allaah brings through it a great deal of 
    good”

    [al-Nisa’ 4:19]

    If it is too much for him and he finds that there is no way to solve the problem or to live peacefully with his wife, then there is no sin in divorcing her; in this case she is entitled to the mahr because the marriage has been consummated. And Allaah knows best.