His curiosity

After finishing a three-course meal, Ji-Soo settled down to drink her second glass of wine.

Watching her lift the red liquid, Kim Ji-hun said, "I thought you were fine with having just one glass." 

"One is not enough for a wine lover like me." Ji-Soo stated and went ahead to enjoy her wine.

"Is that the reason you drink during work hours?" He probed while staring into her eyes.

Instantly, Ji-Soo spit the wine in her mouth back into her wine glass in shock. Seeing the mess she caused herself, Ji-hun quickly passed her a napkin. "You should be careful." 

"Thank you." Taking the napkin from him she used it to wipe the corner of her lips and along her jawline before putting it at the left side of the table.

As she had come back to her senses, she was ready to respond to his statement. "How did you know?"