i'm more sentimental than an average person, so i can't really say what'll make others cry, but 10 years where i loved you the most, damn i'm already almost crying just thinking about it
https://www.mangago.zone/read-manga/cosmic_boy/ (SOOOO ANGSTY, but happy ending)
https://www.mangago.zone/read-manga/itonaga_kun_no_koi_no_ito/
https://www.mangago.zone/read-manga/false_memories_lee_gpiee/ (angsty, then fluffy, then angsty, and then fluffy, one of my firsts and I LOVED this)
https://www.mangago.zone/read-manga/bokura_wa_nando_mo_koi_o_suru/
https://www.mangago.zone/read-manga/mede_shireru_yoru_no_junjou/
https://www.mangago.zone/read-manga/kakkou_no_yume/
Oh shoot did not read the question properly, these won't make you that sad cause they all have happy endings
I am once again here to beg for angst!! Please recommend me some sad BLs that will not only break your heart, but will leave you with crippling depression!! （づ￣3￣）づ╭～