Some people who think it rude when interrupted don’t think it rude to exclude the interrupter from a conversation. Sometimes interrupting is the only way to get a word in edgewise. I am NOT talking about the 2020 US presidential debate, but rather something along the lines of two people engrossed in a common interest or shared memories while a third party who has little choice but to be in the room looks on.
I’m guilty of excluding others in this way. My go-to move, and one I hear others make, is to self-defensively say, Oh, but I never get to see so-and-so, or, It’s so hard to find someone to talk about such-and-such. Both of which might well be true. But this defense would be more justifiable if we lived in an era without internet and other modes of communication. And what it does is tell the third party she’s selfish for unwittingly pointing out our selfishness. How rude!