Marriage.

Yoona thought it would be something that two people choose and decide based on their will. She have always imagined that it is her and Luhan saying I do in front of the altar, wear their respective rings and kiss each others lips like it's the first time. But in her reality, it is not what it seems to be. 

And then there's Shim Changmin, the man she is supposed to marry and completely took away that fantasy in her mind.  He is an upside down of everything that Luhan is but no one told her nor gave her a warning that something like this can actually come up.....can happen.

So she asked herself, what if........no, that's impossible.