David Hume gör i An Enquiry into the Principles of Morals en distinktion mellan nära och flyktiga relationer:

Constancy in friendships, attachments, and familiarities, is commendable, and is requisite to support trust and good correspondence in society. But in places of general, though casual concourse, where the pursuit of health and pleasure brings people promiscuously together, public conveniency has dispensed with this maxim; and custom there promotes an unreserved conversation for the time, by indulging the privilege of dropping afterwards every indifferent acquaintance, without breach of civility or good manners.

Jag ser vänskap som en kontinuerlig variabel; jag har råkat på andra som ser den som binär. Sådana är svåra att förbli vänner med. Det gäller att kunna acceptera att man blir ”dropped” efter lite lättsam konversation.