Himo to Koi no Sumu Tokoro

The serious-minded salaryman Umi meets the handsome Kai at a laundromat. Kai, having just been kicked out of the apartment where he was crashing with a girl, has nowhere to go. Seeing his situation, Umi offers him a place to stay.
Sharing meals, sleeping under the same roof… Umi, who has long felt lonely, finds himself gradually drawn to Kai. Mustering up the courage, he confesses, "I want to be with you, Kai." Kai responds with a kiss, making Umi believe they are finally a couple.
But then he learns the shocking truth—Kai never thought they were dating in the first place…

(Source: Homesha, translated)

Note: Includes one extra chapter.