2-dome no Koi wa Usotsuki

Sumi has hopelessly loved Natsuki since she was 18. Now she's 28-years-old, works at a cosmetics company, and has managed to miss out on most of her prime dating years by pining after one boy. One day, an interesting new cafeteria opens at Sumi's company, a 'garçon' style restaurant staffed by pretty young men. One of those men is Natsuki's younger brother, Satsuki! Satsuki knows about her long-standing crush, and teases her mercilessly. However, when she is crushed by the news of Natsuki's impending marriage, Satsuki helps her save face. Could there be something between Sumi and Satsuki, or is he just messing with her?

(Source: MangaHelpers)

Included one-shot:
Volume 4: Watashi wa Cherry