Worst parents I have two men and two women although neither are a couple.
Oasis A sick arrangement sees Kim Myung Soo force his wife to give up their son to the bosses wife to raise as her own , where he subsequently lives a spoiled and privileged life. Years later Pops arranges his other son to go to prison to cover for the privileged son’s crime. Whew ! This bad bastard of a father gets set up in a drunkenness trap and then a Truck of Doom takes his sorry ass out as dead men tell no tales ☠️

Oasis again , Kang Kyung Hun is the evil bosses wife that received the child.. Over the years she lies to two different men saying that they are the father of the child . She winds up institutionalized due to her mental state as she loses everything.
Castaway Diva has Lee Seung Joon as the Stalker Dad . Well done, I loathed this character and his impact on the story. Aigoo
Good Bad Mom had Ra Mi Ran as a psychopath. Aigoo