No NTR...the girl gave her virginity to a judge of the idol contest (Seems common in this industry). Knowing that her qualification is the foundation to her better future with her Producer.
This author likes to use "almost-NTR" plot to emphasis how the lovers love and devote to each and another; similar to the previous episode, their love grew stronger when they overcome the incidents involving the girl having sex with another man.
Quote from the Producer in the previous episode: "If there wasn't that NTR, I'll never realize how important she is to me, and how badly I want to win her back."
So, enough of my garbage talk. All we need to know is: the girl slept with another man in some desperate circumstances, but she only loves her producer and that what she manners and cares.