Every so often I’ll be at an event, usually a wedding or a business gathering. And I’ll be talking to someone and someone else will come up to the person I’m talking to and just start talking to them without acknowledging me. Often there will be some big hugs-either Hello or Goodbye - between them. Sometimes that’s it. Sometimes the intruder will just launch into some long conversation.
Occasionally I’ll be the one who is approached, maybe as often, but probably not. When that happens I’ll do whatever I can to bring the person I was talking to into the conversation. And when I have to intrude, I always apologize to the third person and try to be as brief as possible, e.g. Excuse me… Harry, sorry I didn’t get a chance to say Hi, I have to run, I’ll call you this week. Excuse me.
I’m also wondering if this is a boy/girl thing. I’m a guy. I haven’t kept count but I think that woman are more likely to feel this kind of interaction is OK.