A key returned quietly can say that a relationship has changed before either person explains how.

Some announcements get made by objects. A key left on a table, a spare drawer emptied, a toothbrush taken home, and the shift is stated without anyone having to find words for it. That can be a kindness, sparing a conversation neither person is ready for, and it can also leave two people with different accounts of what happened. Actions communicate reliably and explain nothing.

If something like that has passed between you, the conversation is still available afterwards and often worth having. And if you are the one making the gesture, a short sentence alongside it saves the other person a long guess.