I have a girl who I have dated for a year. I have gone through a lot with her. She is a good person, always wanting the best for me. She made me stop drinking alcohol. When we quarrel it takes prayer for her to come back, and every time I ask God to give a sign if she mine, He does it. Whenever I cease to pray problems come back. Right now she told me she has found another man. I don't know what to do, whether I should let her go or not. What about the signs I asked from God? She has blocked all communication. I can't even send her daily scriptures. What do I do?
It appears that you are wanting God to make your decisions and He doesn't operate that way. See: Does God send us signs?
A marriage is made when two people choose to love each other. You two have been quarreling frequently. She has left you for another man. Seems to me that it is quite clear that she doesn't want to marry you. You can't force her to change her mind and God isn't going to force someone to change. Even if it were possible, you both would be miserable if she married you against her will.
What do you do? Have a good cry about losing her and then start looking for a better woman, one who is interested in marrying you. Appreciate the fact that she did help you improve, even if she does not want to marry you.