The regret of "what if". The sadness that fades over time, and what's left is that emotion that can't be described yet lingering around. Like a small stick on a flower that you picked on the flower field, suddenly it feels like that summer a long time ago when we were young, but it is not. The warmth feels identical, but the faces have gone. The sky is still clear and bright, but the wind no longer tells the sweetness of love.