https://www.mangago.zone/read-manga/young_good_boyfriend/ this might be a controversial opinion since they started dating when ml was only 17, it also has a prequel and it shows how they became a couple but this one is waaaaaay better
https://www.mangago.zone/read-manga/bokura_no_shokutaku/ my personal favorite in the entire world
https://www.mangago.zone/read-manga/blanc/ perfect ending to a perfect saga
https://www.mangago.zone/read-manga/link_and_ring/ i believe in love based solely on the existence of this manga
https://www.mangago.zone/read-manga/when_the_cicadas_stop_crying/ dont know if this is heartwarming but i cried A LOT and i loved it
https://www.mangago.zone/read-manga/under_my_skin/ an incredible love story between two adults with their own emotional turmoil
https://www.mangago.zone/read-manga/tonari_ni/ this one is just beautiful and so soft and i love it so much
https://www.mangago.zone/read-manga/see_you_later_mermaid/ this one is so perfect and wonderful and the whole atmosphere is just chef's kiss
I want short heartwarming bl that it so heartwarming and wholesome it made you cry