365-nichi Mae no Hanayome - Otoko Tomodachi kara Gouin ni Kyuukonsareteimasu

For some reason, Hinano has been living on a "love-free life" for the past five years. She is so close to her classmate Yamazaki, an ace athlete, that they drink together and stay over when they miss the last train. He is a talented, well-liked, and record-setting track and field athlete, and she has looked up to him since she was a student, but one day, he suddenly proposes to her after just one day of dating!