I am not sure what to do. well first i am getting married to my best friend and my sister is like head over heels for her and i feel really bad that i am marrying her even though my sister likes her. Its going to be an open marraige so if my best friend wants to get with my sister then she can but i am not sure how my sister feels about it. BTW my sister isn't my real sister she is my mothers boyfriends daughter just to let you know. I dont know what to do. Help me.