Do scenes end? Some are quick and dirty, but sometimes they can be dragged out to the point where everyone, including the audience, knows it’s time for the actor to walk away. This is important on stage and in real life: it is okay to leave when the scene is over.
All scenes are essentially the same when broken down: someone wants something from the other person/people. A mother wants her child to clean their room and do their homework; a salesperson wants the shopper to make a purchase; a comedian wants the audience to laugh at their joke.
If someone else enters your scene, it’s okay to acknowledge their entrance and then leave without forcing any type of agenda. And just as it’s okay to leave, it’s okay to come back (as long as you have permission to). It is true for everything in life.
My father used to tell me, “Always leave something to be desired.”