When you finally make all of the Girls in Lover, there will be an ending scene. You will have a choice whether you sacrifice yourself for greater good or be selfish and let her die.
Sacrifice Yourself Edit
You charge yourself towards the Dark Portal. The Dark Portal closes with exchange of your life; and literally saved the world from destruction.
By sacrificing yourself the game will automatically prestige (Soft Reset), there will be a warning note if you planning to sacrificing yourself.
Be Selfish Edit
You decided to let Q-Pernikiss (Q-Piddy) to sacrifice herself in order to close the Dark Portal. The Dark Portal closes, the world is saved; but Q-Piddy is nowhere to be found...
You can still play and date the other girls, but Q-Piddy will be marked as "GONE" instead.