Koisuru Futari No Taion summary:

From Yaoi Is Life: Not a day passed without a man for, the handsome designer, Kanbe. His absolute requirement in choosing a guy is their scent. He's gone out with countless guys already, but has yet to find the one... Wait, there he is! Takahashi-kun, a delivery man, stole his heart and his nose, and Kanbe made a move on him right away. Takahashi-kun is like a puppy wagging his tail at Kanbe with all his heart, but on the other hand, Kanbe starts to feel guilty for what he has done...?