The Two girls stayed standing at the rooftop with both in dazed . They witnessed the same thing but it left them different feeling . 
Sojung can't say if she was shocked or mad to what she witnessed ,but she sure felt something that she can't understand . She already expected to see that psycho act like that towards eunha , she wouldn't even be surprise if jung yerin would make a move to eunha 

why ??

because she's well aware how charming the small girl is - she can captured anyone's heart with her charms and kindness .

But what surprised her the most is how eunha reacted to yerin . She  clearly saw even from a distance how eunha smiled while looking at yerin earlier ,and how she didn't even bother to push yerin away from her- even though she knew that sojung is watching them.

She remembered that while they were still in the states -eunha also had a lot of admirers back then . Since she's famous and charming , alot of students did everything to be close to her and courted her but eunha just brushed them off. Everytime that someone gravitates closer to her - she always made a way to pulled herself away . She pushed everyone who's courting her away from her especially when sojung is there - watching them .

She'd said that she just doesn't want sojung to think that anyone can get her attention away from her ,and she also  said that she always felt like she was cheating on sojung whenever she's with someone she knew has feelings for her(even though it is a one sided love and sojung obviously doesn't feel the same way for her )  .

So seeing eunha reacted like that is new for sowon. After sowon confronted yerin last time , she's now sure that eunha is aware that sojung doesn't like the idea of her being close with yerin and she knew by now that sojung despised the latter. she's expecting that eunha would stay away from yerin because eunha always avoided those people who's making sojung uncomfortable.

But this time - she didn't . She clearly showed to eunha  that she hates that yerin and she's expecting that the small girl would do the same thing but for the very first time - she didn't. she still went to that rooftop with her . 

What's happening to you eunha ?? She kept asking that in her head 

But is that the right question to ask ?

Or maybe the right question is ...

What is happening to you sojung ??

She remembered how relieved she was when she'd learned that the boy that closed with eunha (back in their former university )has a feelings for for the small girl and started courting the bunny-like-girl...

Because back then , she thought that time that maybe she will be free from the girl if that boy manage to make girl fall in love with him  .

So she can't understand why she's feeling like this right now ...

She should be glad just like what she always felt before -Everytime she heard a news that someone's courting eunha . Because yerin -despite her bad reputation - has a way with girls , unlike the other suitors of eunha , yerin is clearly different from them..
She has this undeniable charm that can make eunha fall for her ...

But why she's feeling this ?? 

She'd now found someone who can possibly make eunha fall in love ...

She should be relieve...
But she felt the opposite ...

She's afraid ...

She held her chest as her breathing became unstable and fast ..

Then a realization hits her ..

Maybe I'd never feel this before because deep inside of me I knew  that it is impossible for them to make eunha fall in love with them ...

But now ..

Now im feeling this ,because I am now seeing how possible it is for her to make her fall in love ...

On the other hand

Sinb is confused ..

She saw how yerin smiled at eunha ..

She saw how comfortable the girl with the latter ...

She remembered how yerin always reprimanded her Everytime she go to the rooftop ..

It's yerin's safe havens ..

But why she's just letting eunha to come to the rooftop??

Shes confused ..

She said that she doesn't like to be with anyone ...

But why did she looked so comfortable with eunha ??

Then the scene earlier suddenly flashed in her memories ..

She kissed her .. 

Eunha is in love with sojung right ? So why did she let yerin kissed her infront of sojung ??

And why did yerin have to kissed her ???!..

And what confuses her the most is...

The