WHY ARE THEY PACKING THEIR STUFF WITHOUT EVEN ASKING YIYUN?!!

Because they don't know the whole story yet. They went away leaving their son and his child at home.
Now that they're back they still think those two are still living there.
The CEO in their eyes is just a stranger/son's friend baby sitting rourou.

Now that they are back they don't want to bother the CEO so they are getting rourous things say their goodbyes and go back home.