Outside

"Now that I sang a ballad song, the atmosphere has definitely gone down." He continued with a sigh, "Rina sunbae, it's your turn now."

Suji did not expect Seungwoo to call Rina with her first name.  Did something happen that Suji knew nothing about?

Not like she cared. Suji was not in the position to care about Seungwoo now. The relationship she had with Seo Jinwoo has just broken, and then she was now caring about some other man?

That is absurd. Suji has to think about him too.

But in all honesty, 

How could she even do that one to three months of decency when it was Seo Jinwoo who betrayed her? She could have sued him for emotional anguish!

Well, that was a bit exaggerating. They were in it knowing the harm and benefits it could bring with just them being together.