Aisare Neko wo Hantoubun

Satoshi is a famous novelist under pressure to release another big hit. He consults his friend about having trouble sleeping and is then introduced to a sleep companion, You, who stays with him. Things get naughty fast when his male sleep companion forces himself onto him. Satoshi's editor, Tatsumi, recognizes Yoh and instantly becomes jealous as he secretly has a crush on Satoshi. Despite the age gap, Satoshi is now stuck in a love triangle.

(Source: Renta!)