is because Yoona is not heavy.
There was a scene where Ji Changwook had to run and jump over a cary while carrying Anna.
(The Gif)
*points to Ji Changwook* : A cool Oppa
Ji Changwook: Thanks for being so light, I'll treat you a meal.
caption : Im Yoona already had lunch (before the scene)
But Yoona grabbed his collarㅋㅋㅋ
*caption on Ji Changwook*: *nods* I'm fine.
caption: Stop breathing (very loudly)!!!
-Whoa.. Look at his smile..
-Ji Changwook is such a very sweet guy..
-So sweetㅠㅠ
-They both are equally cuteㅋㅋㅋ
-Whoa.. Brb crying..
-The way he laughs is so cuteㅋㅋ Anyway, Yoona is too skinny..
-'I'll treat you a meal'.. The way he says that is so heart-fluttering..ㅠㅠ
-What drama is this?
-Changwookie..
-Just imagine how light Yoona is..
-Yoona is so pretty.. I mean it..
-Horray for Ji Changwookㅠㅠㅠ
-I'm watching TheK2 because of them..ㅠㅠ
-Whoa.. But she really does look so light..
-Both of them are so good-looking..
-Seems like Yoona has a really nice personalityㅠㅠ Does she lack in anything..
-I can already feel how light Yoona is just by seeing how Changwook carries her..
-Look at both of their visuals..
-He's so freaking handsome..
-How much does Yoona weight? She looks so thin..
-Ji Changwook is very handsome..
-Yoona-ya.. Grab my collar too..