If a person has prayed istikhaarah, he may make a decision and go ahead with it
Question

                I proposed marriage to a girl with the intention of marrying her, then after that I prayed istikhaarah with regard to this marriage. On the same day that I prayed istikhaarah, my family and I went to visit the family of my fiancée, and she treated my mother in an inappropriate manner which led to a problem with my family. Should I regard this incident as a sign from Allaah telling me to forget about this girl, or do I have to continue my relationship with her despite the fact that some of my family are afraid that this girl will damage our family relationships?.
Praise be to Allah.
    If this girl is religiously committed and of good character, 
    and you have prayed istikhaarah asking Allaah for guidance with regard to 
    proposing to her, then go ahead and do not hesitate, for whatever Allaah 
    makes easy for you will be good, in sha Allaah. The sign of istikhaarah is 
    when a thing is made easy. If it becomes difficult and does not go ahead, 
    that is a sign that there was no good in it for a person. It says in the 
    du’aa’ of istikaarah: 

    “O Allaah, if in Your knowledge, this matter (then it should 
    be mentioned by name) is good for me in my religion, my livelihood and my 
    affairs, then ordain it for me, make it easy for me, and bless it for me. 
    And if in Your knowledge it is bad for me and for my religion, my livelihood 
    and my affairs, then turn me away from it, and turn it away from me, and 
    ordain for me the good wherever it may be and make me pleased with it.” 

    The fact that this girl treated your mother badly is not a 
    sufficient reason for leaving her. That may have happened because of 
    heedlessness or it may have been a mistake, or due to excessive shyness and 
    so on. 

    But if it becomes clear to you that this behaviour indicates 
    a fault in her religious commitment or character, then in that case your 
    hesitating to go ahead with the marriage is justified, but if you want to go 
    ahead with the marriage, you must set things straight between your family 
    and your fiancée, and prepare your family to welcome a new member. 

    Conclusion: whoever is sincere in turning to his Lord and 
    delegating his affairs to Him, and prays istikhaarah for guidance in some of 
    his affairs, should go ahead and do it. If it becomes easy for him, this is 
    a sign that it is good for him, but if he is stopped and it becomes 
    difficult, then he should forget about it, and he should realize that being 
    prevented from doing it is good in sha Allaah. May Allaah help us and you to 
    do that which He loves and which pleases him, and may He may the best of 
    things and those which are dearest to him easy for us. 

    And Allaah knows best.