This happens to me a lot at work. I'm in a conversation with a coworker and I can't tell the difference between a pause/change topics and when the conversation is over. I'll frequently start walking away only to have my coworker keep going with a related but different topic - I clearly misread the situation and didn't notice that the conversation was not, in fact, over. I catch myself and come back to keep talking, but it's awkward to have to do that.
On the flip side, there are times when the conversation is clearly over but I don't know how to end it. These end up with me and my coworker sort of staring at each other for a bit and an awkward "well, I'll go do xyz"
It's not REALLY that bad, but it is awkward.
So, how can I non-awkwardly inquire or figure out that the conversation is actually done, and how do I leave politely and, again, not awkwardly, when it is over?