Not all meetings have to be long: sometimes they can only last a moment. Maybe to slow you down so you don't get into an accident, or so you can meet potential love.
When we start a conversation with a random fellow traveler and just can't stop. Or when we just exchange smiles with a person who has passed on a nearby escalator. And it really seems like some kind of unearthly connection that just has to be.
Just because someone doesn't stay in our lives for long doesn't mean there's no point or purpose in meeting them. Everything has a meaning. And it is these invisible threads that connect us to each other that make life in this world so amazingly unpredictable, because we never know when we will meet someone who will make us change our lives.