What does it mean for boys to tell girls to be good?

Boys tell girls to be good, which is usually a sign of love. He called the girl a good girl, which showed that he had a good impression on her and hoped that she would follow his instructions. It may also be that he wants her to be quiet and polite and avoid doing anything that will make him feel dissatisfied. In addition, the boy may call the girl dear because he wants to get closer to her and further develop the relationship. The specific meaning depends on the relationship between boys and girls and the tone of voice.