Tenshi Arles no Renai Kaigoroku

Sakimoto, a high school boy with no romantic experience, is suddenly visited by Arles, a guardian angel, who wants to help him with his love life. The two of them set a goal for him to get together with Mizumori-san, the girl of his dreams, but Arles is a clunker of an angel, clumsier beyond his imagination...! (Source: Tonari no Young Jump, translated)