Stopping talking to someone can be disrespectful.
Bob just stops talking to people mid-sentence when he doesn't feel like talking anymore.
Bob wants to save time on conversations.
Bob starts telling people that he's got to go somewhere before he walks away.
Bob is talking to someone and when he gets bored he stops talking and walks away.
People are still annoyed at Bob, but they are no longer confused about it.
The people are annoyed and confused and don't even know why he stopped talking.