Think back to your own behavior. Did you inadvertently say something that hurt the person? Sometimes we can make a comment that seems innocent, but has a much stronger effect on the person than we imagined. Have you come on too strong? If you are dating and you became serious too quickly, a person may not be ready for a commitment. Were you a good friend? Analyze your relationship. If you rarely argued, repressed feelings could lead to a break up. Constant arguing can become overwhelming and cause someone to break off communication.