Karada de Wakaru Koigokoro (2004)

Blurb:
Kanae Hayakawa is pretty, popular, and sought after. What could possibly be wrong with his life? Everything. Though he’s known as the “Cool Beauty” of his college, the rumors couldn’t be farther from the truth! But there is another boy who has become the talk of the entire college: Yuichi Nagao, notorious womanizer and general jerk. He’s famous too, and like Kanae, it’s for all the wrong reasons. He’s been with more women than he can remember, and it’s earned him a horrible reputation. As fate would have it, Yuichi and Kanae have become fast friends, and the entire school is talking. What in the world is the Cool Beauty doing with the school jerk? As their relationship grows, will they remember to open up and understand one another?

Source: www.anisearch.com/manga/4810