They both center around the theme of infidelity and relationships. In both "First Wives Club" and "Red Balloon," the main characters are dealing with the betrayal of their partners and the consequences that come with it. In "First Wives Club," Bok-Soo and Hwa-Shin team up with Bok-Soo's mother to get revenge on their unfaithful husbands, while in "Red Balloon," the characters are struggling to navigate their own complex relationships and deal with the challenges and heartbreaks that come with them. Both shows also explore themes of love, loyalty, and the search for happiness in personal relationships.