We can focus on themes like cooperation. For example, the girl next door and the main character could work together to plant a garden.
One way is to base stories on kindness. Maybe the girl next door is sick, and the protagonist helps her by bringing her soup and reading to her. This promotes positive values rather than negative ones.
To create positive stories, we can think about community. Suppose the girl next door and other neighbors come together to organize a neighborhood clean - up. This kind of story encourages positive social interaction and a sense of community, which is much better than stories with inappropriate or negative themes.