Back story: This issue started over a year ago. My niece and my son, both very good friends in their late 20s, both in committed relationships who talked often, hung out together - even going out drinking without their partners.
One day she decided while out drinking with my son and driving around to hang out the car window and raise up her top (nothing under top) and doing other inappropriate things while my son hung out with her. My son, shocked but said and did nothing. Then sometime after that while texting my some made inappropriate comments that she took offense to and now she refuses to attend any family gatherings if my son is invited. She even refuses to allow my son to apologize. She won't forgive or allow second chances.
Everyone, including her mother believes this has gone on far too long but no one wants to say anythingfir fear my niece won't come around any more. So now we have two different holidays such as Christmas and even just BBQs- one for when my son attends and one when he doesn't. He's a single dad of three boys. Not the whole family gets to see them because my niece.
Present day: My parents are throwing a graduation party for my niece and she refuses to have my son invited. It's a full family gathering. WIBTAH if I finally just tell her what the rest of the family believes. That she needs to stop this behavior. Also, I have decided that if my son isn't invited I won't attend not for making a statement per se but because I truly feel guilty attending when my son can't.