Basically I need some advice with my friends. I'm gonna use letters to make this more easy to understand. My close friends are group A, and some other people I know are group B. I'm friends with group B but not really that close to any of them if that makes sense. Now if group A were to do something, they'd most probably invite me, however group B are now starting to invite group A to lots of things and I feel quite isolated. What shall I do?