amari

These are some popular ones, so you might've already read them
10years that I loved you
Timeless melody

There's blue flag, it's not a tearjerker but I found it raw and sad, it felt real in a way that was suffocating yk
I FOR SOME REASON AM UNABLE TO REMEMBER ALL THE SHI THAT MADE ME CRY SO IMMA GO RECOMMEND SOME MORE AFTER I THINK SOME MORE

Haruka Tooki le (Faraway Home) still makes me sob to look back at. I also second the person who said Timeless melody. I'm pretty sure I cried at that one too.
https://www.mangago.zone/read-manga/haruka_tooki_ie/

Sorry, I should warn you that Faraway Home deals with religious trauma in case that makes you uncomfortable to read about

LMFAO I KID YOU TF NOT, I ADDED HOME FAR AWAY THE FIRST WHEN I WAS JOTTING DOWN THE SHI THAT MADE ME CRY,
Also to add to the list
Banana fish, hotarubi no mori E, painter of the night was pretty painful at times

Timeless melody just crushed my soul

These are all GLs:

Completed:
https://www.mangago.zone/read-manga/run_away_with_me_girl/
https://www.mangago.zone/read-manga/to_die_in_june_one/ (read the last two chapters here: https://www.mangago.zone/read-manga/to_die_in_june/)
https://www.mangago.zone/read-manga/oniisama_e/
https://www.mangago.zone/read-manga/living_will/
https://www.mangago.zone/read-manga/seasons_in_bloom/
https://www.mangago.zone/read-manga/kago_no_shoujo_wa_koi_wo_suru/
https://www.mangago.zone/read-manga/huijin_huayuan/
https://www.mangago.zone/read-manga/vampire_chan_junior_chan/
https://www.mangago.zone/read-manga/yume_no_hashibashi/
https://www.mangago.zone/read-manga/composing_spring_in_this_room_where_cherry_blossoms_bloom/
https://www.mangago.zone/read-manga/kimi_to_tsuzuru_utakata/
https://www.mangago.zone/read-manga/haru_and_midori/
https://www.mangago.zone/read-manga/ohana_holoholo/
https://www.mangago.zone/read-manga/throw_away_the_suit_together/
https://www.mangago.zone/read-manga/getting_to_know_grace/
https://www.mangago.zone/read-manga/i_love_amy/
https://www.mangago.zone/read-manga/the_sound_of_a_butterfly/
https://www.mangago.zone/read-manga/sayonara_rose_garden/
https://www.mangago.zone/read-manga/this_love_that_won_t_reach/ (age gap, MC is in love with her sister-in-law;rushed and ambiguous ending)
https://www.mangago.zone/read-manga/the_story_of_a_person_who_grew_a_flower/ (short story;age gap, teacher-student relationship;hanahaki disease)
https://www.mangago.zone/read-manga/final_film/ (short story)
https://www.mangago.zone/read-manga/shiroi_heya_no_futari/ (one-shot)
https://www.mangago.zone/read-manga/saudade_ni_kuchidzukete/ (one-shot)
https://www.mangago.zone/read-manga/141108/ (one-shot)
https://www.mangago.zone/read-manga/aliens/ (one-shot)
https://www.mangago.zone/read-manga/the_story_of_the_princess_and_the_little_mermaid/ (one-shot)

On-going:
https://www.mangago.zone/read-manga/kono_koi_wa_hoshi_ni_wa_negawanai/
https://www.mangago.zone/read-manga/the_wind_spell/
https://www.mangago.zone/read-manga/dark_mermaid/
https://www.mangago.zone/read-manga/tower_of_campanella/
https://www.mangago.zone/read-manga/kimi_ga_shinu_made_koi_wo_shitai/
https://www.mangago.zone/read-manga/a_monster_wants_to_eat_me/
https://www.mangago.zone/read-manga/artificial_temperature_36_7_c/
https://www.mangago.zone/read-manga/have_a_great_trip_after_the_credits_roll/

Thank you