DY: R’ Moshe says his assumption there, black on white. He thinks having a friend who is a girl is always inherently Derech Chibah because why else would you be friends with the girl instead of with boys. Depending on the community, that logic doesn’t always apply.
And, in many cases in these communities, couples from 9th and 10th grade end up getting married. They just aren’t ready for a few years yet.