Imagine you have a toy box with lots of different kinds of toys: cars, balls, dolls, and blocks. When you want to play, you might pick out one toy and play with it for a while. But then you might get bored of that toy and want to play with a different toy.
Now imagine that instead of toys, we are talking about people. Sometimes, grown-ups like to have special kinds of friends called girlfriends or boyfriends. Just like you might get bored with a toy and want to play with a different one, some grown-ups might get bored with their girlfriend or boyfriend and want to have a different one.
This is called “promiscuity” when people have a lot of different girlfriends or boyfriends without being very loyal to just one person. Sometimes, people can get hurt or feel sad if they think their boyfriend or girlfriend is being promiscuous. It’s important to be honest and respectful to the people you love and to make sure everyone is happy and feels good about the relationship.