Sure.
If there is *cause* in a legal sense, morally, ethically, your safety, security, health...yes.
For all others/else, I think you have to go by what makes sense for the closeness of the relationship.
You might have a coworker with whom you are much closer than your immediate family, so *that* person might well deserve an explanation/a "goodbye" before your family.
Every pairing is a different relationship; only you can figure out what your own level of connection with someone is, and whether or not they deserve/are owed an explanation. And your own evaluations might be quite different from their evaluations.
