How to be accepted back into a group
For this site to work I really think that we have to limit ourselves to well focused questions. Questions need to focus on specific situations and the skills to use in them. There's no single interpersonal skill which you can point to for solving the problem of a mean or unaccepting friendship group - it will take dozens of interactions and dozens of skills. Answers will make lots of assumptions and veer off in widely different directions.
I suspect these questions may be so common that they would warrant a custom close reason.