At first, the music box was an instrument played by royal nobles and dignitaries. Because it can be played automatically after winding, it was a highly automated musical toy at that time, so it was more precious. Things are scarce, and giving music boxes to friends can better reflect the importance of friends, so many people in modern society choose music boxes when expressing their feelings.
In love, the music box stands for "I hope she will think of herself when she sees it".