"What's wrong mom?" Tae Jung asked when he realized that his mother had been daydreaming and silent in his room for more than a month. "Did Eun Ra make you uncomfortable? I'll ask her to fix--"
"No, not him." Su Ri chose to answer with a completely honest answer. "Then? I don't want to argue with mom for the umpteenth time. If mom doesn't like Eun Ra then let me like her alone, I don't mind that opinion. Don't take my life seriously." Tae Jung again discusses the uncomfortable feelings that have been haunting him lately and managed to make him uncomfortable.
"Yes, Yes, Yes." Tae Jung didn't answer seriously, this time he chose to sit on a chair next to his mother where Min Su Ri was alone on the balcony of her room.
Tae Jung deliberately entered because Eun Ra told him that his mother was not okay, not fine in the sense that she needed someone else, and Eun Ra's success could not accompany him at all.