I recently was at a party and was kind of shocked at how many people don't follow what I considered to be the norms of group conversation. When a conversation circle forms, I think it's polite to acknowledge other people. If someone new joins the circle, at least say hello or acknowledge them with body language. It's uncomfortable to walk up to a circle and feel iced out because no one even looks at you. I also think it's rude to monologue or tell everyone your whole life story. It's appreciated to engage with other people, and give them the opportunity to talk.

I think some of the people were just socially awkward and clumsy, but I also suspect some people are still mentally High School and were ignoring other people on purpose.