It’s pretty common for kids that age. In fact most of us had our first crush/loves/person they wanted to marry at that age and it’s usually was an older relative or caretaker. This is because they represent our first understanding of love and security. Not all of them hold that crush for so long but it can happen and I’d say Aoi’s situation is pretty typical.
I do get that but seems like adults really need to be conscious of kids interactions because it is possible for abuse with their feelings. There were many situations I know as as a preschool that I know kids thinking of having lovers, having kids, or playing house is very dangerous. I can't remember a lot of things around 4-6yrs old but man boys are dangerous even as kids.
why are so many dramas and manga shows kid as below 10 deciding to marry?????????? what the ef.... be kids!!!! not dream about getting married and have a love life ... arrrggg