Love

Now that u mention it I actually read something similar i was gonna rec but i cant find it

it's not as messy as this but the younger brother also was in love and quietly watches the one-sided unrequited love of his brother's friend.... i think they're roommates too..? Ugggh i cant remember at all.....

Oh that’s sounds delectable wait-

oh my god i know the one you’re mentioning but i cant remember it

was the brother married too?? if u rmbr let us know i've been looking for it again but cant find it

i have a list for similar tropes! https://www.mangago.me/home/mangalist/1689779/

but here are a few specific to relationships with the younger brother:
https://www.mangago.me/read-manga/deisui_shite_osotta/
https://www.mangago.me/read-manga/empty_heart/
https://www.mangago.me/read-manga/kare_ga_megane_o_hazusutoki/
https://www.mangago.me/read-manga/furimuite_tsukamaete/

Thank you thank you boo!!