A yaoi manga and mc is a delinquent or gang member i think who loves action movies. There is this one movie he really loves where the character sacrifices his life for his ‘aniki’ and mc thought it was a noble sacrifice (other people or gang members i think knows that it was because the character loved the aniki). It was only after doing stuff with ml he realized that it wasn’t because of ‘loyalty’ but because the character loves the aniki. There was a line that mc says “(character name) you traitor”. Thank you!
Following because I also want to know. Reading your description reminded me of this one though.
https://www.mangago.me/read-manga/apron_yankee/
Also read the sequel
https://www.mangago.me/read-manga/sensei_wa_butchozura_shite_yatte_kuru/
This chapter was like my first sip of water after going through the effing parched desert of chapters of misunderstandings. Now my loves do go on and lay it all on the table so i can now be thoroughly quenched of this thirst.