Tabetaku Natchatta

When they joined the same company after graduating, Jin and Akitaka hit it off as coworkers right away. Ten years have passed since they started living together to save money on rent, and they have settled into a comfortable family-like relationship, but then a "change" comes over them...? A gradual live-in love story between a friendly, outgoing guy and a cool, introverted man, by Tsunechika Obata, a master of romantic comedies.

(Source: Homesha, translated)