You decide not to come back the next day.
So the days go on as they did before. The same routine you've done day in and day out your whole life, with the exception of yesterday.
Sometimes you think about the girl, how she is, if she came back, if she ever forgot about you or if she still thinks about you. Or even looks for you.
But you keep going along as you did, with that one day a fun memory. A fun thought of what it could've been.