Conversations don't end when we want them to
In fact, on average they last twice as long as desired, according to some new research at Harvard, which concluded that the reason for this is a 'coordination problem': conversants have no idea when their partner wants to end and think their partner wants to keep going.
The reason for this 'unsolvable' problem is that conversants require information they usually keep from each other to know when to end a discussion.
We usually end conversations through highly routine practices, they noted, such as re-stating the reason they started the conversation ("Well, I just wanted to see you you were doing") or making arrangements ("So let's sort out what time on Monday").
*Do conversations end when people want them to? Adam M. Mastroianni et al.