Yoo Hae-jin, a household name in South Korea’s entertainment scene, took on his first-ever role in a romantic comedy in “Honey Sweet,” a lighthearted film that portrays the love story of a middle-aged couple. Yoo plays Chi-ho, a nerdy, workaholic researcher at the confectionery firm who falls in love with Il-young (Kim Hee-sun), a single mother and a remarkably passionate and optimistic phone operat...