In "A Valid Love," Um Tae Woong witnessed Lee Shi Young's affair in front of his own eyes. Nonetheless, he let it go and didn't say anything.

On the episode of tvN drama "A Valid Love" broadcast on December 29^th, Jang Hee Tae (played by Um Tae Woong) was following Kim Il LI as if spying on her. Then, he saw Kim Il Li going into Kim Joon (played by Lee Soo Hyuk)'s working laboratory.

Jang Hee Tae followed them and saw through the reflection on the door that Kim Il Li and Kim Joon were hugging each other. He got extremely angry. Nonetheless, there was absolutely nothing that he could do.

Jang Hee Tae wanted to go right away to the work scene but he could not do that. He said to himself, "Whatever I see, it'll be even more than what I imagine. Even if I want to pretend like this never happened, I can't."

Meanwhile, tvN drama 'Valid Love' features a story of Kim Il Li (played by Lee Si Young), her husband Jang Hee Tae (played by Um Tae Woong). In the drama, Kim Il Li ends up having an affair with Kim Jun (played by Lee Soo Hyuk), who falls in love with Kim Il Li.