I'd say it's an entirely different thing to vanish from an event than to vanish from a conversation. Vanishing from an event early can be seen as considerate:

I'd say it's an entirely different thing to vanish from an event than to vanish from a conversation. Vanishing from an event early can be seen as considerate: you don't want to spoil other people's party mood with your goodbyes and by having to decline the invitations to stay a little longer or to join an afterparty. You just vanish and let others party on. The more alcohol is involved, the less anyone even notices. But vanishing (walking away) from an active conversation without any concluding ritual or external interruption is just perceived as rude.