"it's not you, it's me"

So, I have kind of a unique situation in that upon moving to foreign country, I sort of inherited a teenager when her parents died. I tried to adopt her legally, but she doesn't have citizenship in her own country (whole other story) so it was never finalized, but I have been her mom for 2 years now. She is now 16, and we had been having the same old fights that all 16-year-olds do about chores, homework, etc. The difference is that because we are in her culture, so she has nothing to compare it to. About a month ago, we went to see a counselor (from her culture, not US) and she basically said that if things didn't change, she wanted to go live with some other friends of ours from her own culture (they run a children's home with 11 other kids). The past month has been a lot better, no fights, she has been doing her chores and she seems happy and doing well in school. Today, after we just went grocery shopping and I bought her new shoes and new badminton rackets and she is acting like she will be here for the forseeable future, she says out of the blue that she wants to move out to live in the other house. She assures me that it's nothing I've done wrong, but she thinks it would be more fun to be with people of the same culture. Hard to fault her on that. But, not sure how to react. I want to just hole up in my room and cry because I feel like a complete failure as a human being and as a parent, but that probably isn't very healthy. There really isn't anything I can do to stop her, since the adoption was never finalized, but after two years, I certainly feel like her mother and don't want her to move out. Advice?