One possible reason could be that the boy misbehaved towards the girl. For example, if he bullied her at school or in the neighborhood, the mother might feel the need to discipline him. Another reason could be that the boy did something that violated the family's rules while in their home, like breaking a precious item or being disrespectful.
In some stories, the boy might have been causing trouble in the neighborhood where the girl lives. For instance, he could have been vandalizing property or being a nuisance. If the girl's mother caught him in the act, she might have spanked him out of frustration and a desire to stop his bad behavior right away. But this kind of physical punishment is now considered inappropriate in many places, and alternative methods of correction are preferred.
One reason could be that the boy was being disrespectful. For example, if he was using bad language in the friend's house, the mother might spank him as a form of punishment.
The new mother may be under a great deal of stress. Taking care of a new baby is extremely challenging, and if she has other children as well, a misbehaving child could push her to her limits. She might think that spanking is a quick way to get the child to stop the unwanted behavior, like if the child is constantly fighting with siblings or making a mess right after she has just cleaned up. But again, there are better, non - violent ways to handle such situations, like teaching the child about consequences through positive communication.
Perhaps the boy used bad language in front of the friend's mom or the family. In some families, using inappropriate words is considered a serious offense and might lead to such a punishment. Also, if he was causing a general ruckus and disturbing the peace in the household, the friend's mom could have spanked him as a form of immediate discipline.
One reason could be for fun. Maybe the mother just wanted to have a laugh and see how cute her son would look in girl's clothes. For example, during a family photo shoot or a special family event like a themed party at home.
One possible reason could be that the boy did something really disrespectful towards the girlfriend or her family. For example, he might have been rude to the mother directly. Another reason could be that he got the girlfriend into some serious trouble, like getting her involved in dangerous or unethical behavior.
One reason could be to show authority. A friend's mother might feel the need to discipline another child if they are causing trouble in her home. Another reason could be a lack of proper communication. Maybe she didn't know how else to get the child to stop misbehaving. For example, if the kids were being too rowdy and not listening to her requests.
Such stories are not very common. In most cultures, spanking is considered inappropriate behavior towards adults or near - adults like a son's girlfriend. If it does happen, one reason could be that the mother strongly disapproves of their relationship and is acting out of extreme frustration or a sense of over - protectiveness of her son.
One possible reason could be that the child broke a very important rule, like cheating on a test in the case of a teacher, or lying repeatedly to the mother. However, this still doesn't justify spanking.
In some stories, it might be due to the strict parenting beliefs of the time. Parents or caregivers might have thought spanking was a way to correct misbehavior. For a diapered boy, it could be that he was at an age where he was not fully toilet - trained and still in that stage of being disciplined while also being taken care of in terms of diapering.