is it cheating?

» A week has passed since the incident, and Kai and Suk Hee are doing their utmost best not to wear their feelings on their sleeves.  As if only sweeping a stray leaf from their laps, the two have brushed off the new and refreshing sensation they felt for and with each other. Their practices went on as usual and they tried their very best to kep their feelings under their masks, so to not hurt themselves and, most importantly, those around them. 

"Good morning, Suk Hee," Kai waves at her as he enters the practice room with Krystal. Most days that they practice, Krystal is usually there to observe and spend more time with Kai as well. Their busy schedules prevent them from spending the the amount of time they want to with each other. When the practice is on a break, Kai and Krystal go on walks with each other and usually come back with a snack and tea or coffee for them two and Suk Hee. Even though they almost always bring something for her, she would decline so that Krystal wouldn't make a big deal out of the situation. A few days ago, Krystal pulled Suk Hee aside...

>A few days ago<

"I'm not stupid. I can tell when something is wrong. Especially when it has something to do with MY boyfriend. So I'll just warn you right now, back off. You may not be doing anything 'BIG' right now, but I know that just you being here - you being around Jong In - makes me uncomfortable. I know this isn't me being friendly, but I hope you understand," Krystal looks at Suk Hee dead in the eyes and, with much gusto, warned her. 

"Wait, I don't know-"

"Don't play dumb. Just take it as it is. Let's not prolong this awkward conversation any longer," Krystal cuts Suk Hee off, then proceeds to walking away as if nothing ever happened.

>End Flashback<

With that moment in mind, Suk Hee decides on how to act around Kai and Krystal. 

"I'm home," Suk Hee announces as she takes her shoes off and enters their house.

"Oh, welcome home! Dad's at work still, he'll be home in a little while. How was the tutoring?" Suk Hee's mom goes up to her and hands her a glass of water.