Love & Secret (달콤한 비밀)

Ah Reum (Shin So Yool) becomes a single mother while studying in the US and returns home. And here is a man named Sung Woon (Kim Heung Soo) who is deeply hurt by his family. One day, Phillip (Yang Jin Woo), the biological father of Ah Reum's child shows up in front of them.

Sung Woon decides to take care of the child and protects her from Phillip who seems to be busy enjoying his life.

This drama features these three characters who challenge themselves to succeed in their career, love, and family business.

(Source: DramaWiki)