The Missing Piece by Kun Yi Wei Lou

Ever since an incident three years ago, art school graduate Shen Mo hasn’t been able to paint with his right hand. He’s currently working a desk job in a company owned by the Ji family, one of the wealthiest families in the city. Unbeknownst to his coworkers, however, he has a far more important role: the fake lover of the Ji family’s young CEO, Ji Mingxuan.

Ever the perfectionist, Ji Mingxuan makes Shen Mo put on the full act, both in public and in the bedroom. Their fake relationship continues this way, until Ji Mingxuan’s sister returns from abroad with her boyfriend—Shen Mo's ex.

Once the four are reunited, the nightmares that Shen Mo has tried so desperately to escape catch up to him at last. As the lovers’ acting becomes more and more real, Shen Mo begins to learn about the things that Ji Mingxuan is keeping from him, as well as the truth of what really happened three years ago.

Only one question left:
What will become of a love founded on pretense?