Should there be one more stage between “约会”状态 and “恋爱”关系，when people are having sex？ Or “Sex” itself means men formally plege to
go into “恋爱”关系？Or, who wants sex, then that person lose the "dating" privilege, and thus committe to “恋爱”关系？
I believe， there should be one more stage， let‘s call it：“Sex Stage”。
