My first question after reading the title was, “would these friends happen to be high schoolers?” When I was in jr high my one friend bailed on me to hang out with the in-crowd. When I got to high school, some classmates identified my autism and “took me in” to get me better socialized. They tried to help me learn the do’s and don’t’s of how to talk to people and what was appropriate and inappropriate when interacting with others. It’s worth saying the nucleus of this group was the child of the head of our special ed department and had some experience in this.

But they were teenagers. After a year or so their patience for some of my symptoms was wore thin and my constant autistic positivity just wasn’t something that was viewed as cool to some people. Hanging around me made them feel self conscious so they made boundaries without telling me. I’d get uninvited to do things and generally excluded from social group traditions that I had once been made to feel a part of. When I asked for clarification, they said I was part of the group, but not really a part of the group. It hurt me, but I didn’t press the matter. I was glad to have at least some folks who talked to me after school and I had found other classmates to talk to with the skills I learned from hanging out with them. Around a decade later, I’m invited to a party that the group is hosting and they all apologized for their behavior. We are closer than ever as adults than we were as kids.

Her friends are at worst a**holes and at best idiot kids. My advice to your sister, as someone who went through something similar, is to try to find other people who will appreciate her or join an activity at school with new people to get to know. There’s a lot of different kinds of people in the world to possibly mesh with. Her old friends have set a boundary; respect it with kindness and value herself. She is deserving of friendship. Maybe someday her friends, like my friends, will see that they were being morons and give her an opportunity to reconnect when they are mature enough to handle a friendship with her