@SuperRobotSolo, first, it's not a paedophilia in this case, she just teasing him, she doesn't want to fuck him.
Secondly, people are usually not fine, when the teasing makes the child uncomfortable. But if the child himself is fine with it, there is no problem with teasing, as long as the line isn't crossed, and she isn't trying to literally seduce him.
Thirdly, despite all the talks about equality, men and women aren't actually equal. Very few girls would like to be teased by a grown man, but vast majority of boys will likely enjoy getting teased by a young and cute woman. Because different genders perceive the world differently.
I don't even understand where is the problem there, if no harm is caused to the child. Laws about pedofilia exist to protect the children, since they normally can't speak for themselves in those kinds of situations, due to shock/losing control of their emotions. But in this particular case it's very clear that she doesn't wish any harm to him, and he obviously enjoys it. If she was actually trying to seduce him, it would be a different story, but in this case interfering will only make things worse for both of them.
In my eyes they have a health and wholesome relationship without a hint of abuse or manipulation, so there is no reason to call it pedophilia or involve the law.
I know that grooming exists, but in grooming intent also matters. The main problem with grooming is that the older person forces his desires, opinions and wishes on the vulnerable younger person, and affects their growth as a person in a potentially harmful way. If there is no malicious intent or psychological/physcial abuse, it's not grooming. Not every kind of close relationship between an adult and a child is grooming and/or bad/illegal.
I repeat, the law is here to protect the children, not to harm them and their loved ones. In real life it's not always easy to differentiate whenever an adult has malicious intent or not, that's why they almost always get charged with a crime, just to be safe, even though there was no actual crime (but in vast majority of cases there was).