Eh, the dating bans are because fans expect their idols to be "pure" and "virgin"; the thought of them being with a man ruins that image and can even spark outrage from the community (mostly consisting of very obsessed 20s-to-middle-aged men.) It's not so much about being socially conservative as it is ruining a bunch of guys' fantasies because women should be "pure."

And a lot of K-pop songs have to do with relationships— just not actual ones.