Song Cong is a main character too, right?

So, right after Song Cong changed school, I don't know what the writers are doing here, what is happening, but I am feeling that they are letting Song Cong left behind in so many episodes. It feels like he doesn't belong with Qi Chi and Huan Er's circle anymore. It's so sad and unfair to him. He is increasingly with less screening time alongside with them.