Struggle with Teen relationships

Last night at HC, M asked right after our meal if she could go on home. There were several other teens there so I encouraged her to spend time trying to relate to them. She really didn't want to but chose to go ahead and obey me and I saw her sit near them with her food. After observing(they are the same age but mostly a grade ahead) and recognizing they weren't going to make any effort to try to include her, I told her she could go home. Yes, she could have sat closer, and tried to insert herself into the conversation but this would be very difficult for her to do. For the life of me, I can't understand why they can't include her. What would be so difficult about noticing her, inviting her over and trying to include her in the conversation? It seems like it should be a "safe" place to practice these skills, but it is not--which makes me question our involvement in house church. So, what am I to do? My first reaction is anger--I have seen this occur often throughout this past yr. I know it happens at the school, also. I get extremely angry at my friend, whose children are members of our house church. Why can't she encourage them to step outside of their comfort zone and include her in? I hear continuously from this friend, about how they have a house full of teens--I see her teens bring different friends to house church and when her same age daughter and my daughter are the only two there they seem to get along just fine. But, when her dd brings her friends, M is ignored. Even to the extent that at one event when there were placecards on the table and M was placed at their table, one of them commented...."Who is ______" and pronounced her name wrong. (This was after months of attending the hc) After my initial anger, I try to make excuses for them but the excuses are getting old. I try to rationalize and think, "maybe it's totally M's fault," "maybe she just can't relate in groups of people." I want to talk to my friend about it but I feel such intense hurt about the issue it is very difficult for me to do this.
So, what am I to do? Do I talk to the other mother's in the house group? Do I just let it go (I'm sure that is what my dd would prefer that I do) Do I need to die to the expectations that my daughter can relate to a group of teens and just recognize that she will just do better with one on one relationships--always feeling left out in group? I need wisdom.....