If I'm in a room with people I know and I plan to leave the room for a long time, I tell them where I'm going. If it's for a short time I do not.
What (if anything) is an appropriate time scale to leave a room without announcing when/if you'll be back?
My girlfriend would be very unhappy with me I spontaneously left for a couple of days in this way.
"Alright, see ya later, babe!"
finally shows up after five years
"I said 'later'"