Search Results: immature around his friends

My boyfriend and I have been together for couple years. We lived together for 2 years. I trust my boyfriend 100%. My boyfriend loves me a lot and I am very confident. They did started off as fooling around with each other but after they had sex, they decided they will be better off as friends. I have no doubt that he is not attracted to her anymore.
My boyfriend has couple serious relationships before me. Seems like it's common that she makes his girlfriends feel dislike/disrespected. They've been best friends for at least 7 years. I have no problem at all with them being best friends if she did not make those immature move of hers. When we were first dating, my boyfriend was excited for us to meet. However, she obviously was not. Probably around 3-4 times, she last minute cancel plans or simply, not show up. She didn't even show up for my boyfriend's birthday party (also last minute). When we moved in, every week she asks my boyfriend out on weekends. My boyfriend won't leave me home alone, so he lets her know that he's bringing me. She then disappears or cancel the plans. It's pretty obvious to me that she not liking my existent. When we finally met, I was being very kind and nice hoping that she would accept me. However, she seemed okay but later on, I found out she wasn't. She won't accept me as a friend on Facebook or follow me back on twitter. Fast forward today, she don't really ask my boyfriend out anymore because he would bring me along. She only comes out if I am not there. I talked to my boyfriend about it however, he doesn't find anything wrong or he feels something is that off. He said she might just not like hanging out with me because we are completely different. I told him that her behavior is making me question of her intentions. My boyfriend said he would too if he was me. But he said really nothing to worry about because he doesn't like her and she's like a sister to him. If she does try something then he would tell her off.