Rules Of Dating (2005)

Cast
Park Hae-il (박해일) as Lee Yoo-Rim
Kang Hye-jeong (강혜정) as Choi Hong
Lee Dae-yeon (이대연)
Park Grina (박그리나)
Seo Yeong-hwa (서영화) as language teacher
Lee Young-sook (이영숙)
Lee Hyeon-jeong (이현정) as Hong's mother

Trailer

Synopsis
Lee Yoo-rim is a high school English teacher. He's cute, clever... and shameless. Choi Hong is a student teacher, even though she is one year older than Yu-rim. She's cynical and always plays hard-to-get when a man shows interest in her. While going out for drinks one night, Yu-rim suddenly tells Hong that he wants to have sex with her. Hong is hardly impressed. And so begins a battle of will and wits, both between each other and within themselves, as both Yu-rim and Hong are unsure of what each other wants and what they want themselves. Dating and desire mix explosively. What is the point of this strange relationship? What is the object of their desire?