One of my sorority sisters did this to me not to long ago, and not only did I hear it from someone else, but she had told my friends to lie to me about it because she didnt want to hurt me... hmmm guess she knew she was wrong. In my opinion their is an unspoken rule that you at least need to talk to your sister before you date anyone she has dated to see how she feels about it, becasue your sister is more important than some boy. But lucky for me I found someone who treats me so much better, and so will you.