My daughter does this as well. I have noticed it for a couple years now. She does this at school, extra curricular activities at home and at parties. She is perfectly fine being on her own. It is me who gets upset by this. I have read a few things that help explain this behavior, such as the possibility of having an introverted personality. These kids are perfectly happy not being with a group, not following them, not paying attention to anything else. They are ok being alone. It’s hard to watch as parents. I remember going to a school assembly and my child did not sit with her friends, but more off to the side by herself. And it didn’t seem to faze her in the least. It was at that moment that I started asking her questions about things and looking up reasons for this… of course I have also learned that too much research is bad too. 😊 And I think it may also be a trait of ADHD. My daughter was diagnosed as ADHD – Inattentive type.