Well, I think there is such a thing as being too close to your family. Besides, I thought he considered me family as well. It's rude to ignore other people in your life if you really truly care about them and it's rude to just blow off plans with your gf at the last minute to go see your family (unless of course there's an important emergency, but he did not say there was). If he wanted to see his sister that badly, he shouldn't have made plans to spend time with me. I never did that to him and I wouldn't. He is acting like a jerk who does not care about my feelings. I now get that my ex bf did not truly care about me or he stopped caring somewhere along the way. If he's willing to do that once, then it means he'll do it again in the future and there's no way I can trust him.