Thread: Boyfriend's Sister

I was dating this guy for about a year and a half, we recently broke up because he does not stand up for me when his sister treats me like the scum of the earth. He has been wanting to get back together but I do not see how I could be serious with someone who has a family member that hates me and isn't mature enough to be civil.
I met my boyfriend at a party when he came to visit his sister at our college. I was acquaintances with his sister but never really friends. She always seemed really nice but once I started dating her brother things just got awkward between us. I just overlooked them at first but the more serious the relationship got the worse she treated me. She started out by just being really short with me when I tried to make conversation with her. Then she escalated to making rude or unwelcoming comments, for example, she once said "he's my brother I have to deal with him but you choose to." My boyfriend would always invite her and her boyfriend to hang out with us and she always refused and never made any effort to be friendly or even civil. If I don't say hi to her first she won't say it at all and if I do say hi she says it as fast as she can then walks away. She always leaves the room if I walk in and if I see her on campus she speeds up as if she can't get away from me fast enough. It is really immature but her behavior bothers me and it bothers me that we can't be civil and that my relationship suffered so much because we couldn't be. It also bother me that his family has to deal with this and for the most part unless she does something bluntly outrageous enough everyone in his family sides with her. My boyfriend tells me to be the bigger person or just ignore her but he isn't willing to confront her and he never lets me confront her. If he was serious about me wouldn't he want to see this resolved somehow? She has been trying to break us up for a while now and it has finally worked. She always speaks about me behind my back and my boyfriend defends her even though I have heard it for myself. She is always really nice to him when we are in a fight and tells him to break up with me. She claims to want to spend time with just him and that I'm interfering with that but when I was gone for 3 months this past summer (studying abroad) she not once made any effort to hang out yet as soon as I got back she wanted to do everything with him. She has even told her mother that she doesn't want me in their house and one day began crying until her family asked me to leave, I didn't even say a word to her that day. She is always throwing tantrums and crying in her house and her own mother complains about it and they all just encourage this behavior by giving her what she wants so that she'll calm down. Everyone who hasn't seen this thinks she is so nice and assumes I must be the cause of all the problems. I used to feel really guilty like this was somehow all my fault and I used to try to fix it but it seems the more I try the worse it gets. And I no longer feel like its my fault because I learned that she has treated all her brother's serious girlfriends badly.
I don't know what to do because I love him and I really want to take him back but all our fights revolve around his sister and I just don't see how we could get passed that, especially if he isn't willing to do anything about it. This issue has really been bothering me to the point where I question all my actions and I even have considered therapy. I really need advice because I am so torn.