https://www.mangago.me/read-manga/stigma_marloong/
One of my all time favorites. And it's happy ending so a win for humanity after the betrayal that was bananafish
https://www.mangago.me/read-manga/mo_dao_zu_shi_novel/
What can I say it's the greatest.
Untamed (the drama adaptation) is also very good even though it's censored the love is there
https://www.mangago.me/read-manga/10_years_where_i_loved_you_the_most/
Ml is an irrelevant red flag hate that guy but you asked for trauma and we're mostly in mc's pov
https://www.mangago.me/read-manga/rent_boy/
(I actually don't recommend this because the ending was so stupid but the art is good and it hurts alot. Just pretend the ending didn't happen. Ml not the greatest person)
https://www.mangago.me/read-manga/madk/
You asked for trauma i shall deliver (warning though it contains gore but I don't know how else to describe it... it's beautifully drawn)
These aren't that trauma inducing but they do hurt a lot at some point. And they do linger in the mind.
https://www.mangago.me/read-manga/ways_of_parting/
https://www.mangago.me/read-manga/incidentally_dyed_by_spring_s_love/
https://www.mangago.me/read-manga/aporia/
https://www.mangago.me/read-manga/ouroboros_1/
https://www.mangago.me/read-manga/a_proxy_painter/
https://www.mangago.me/read-manga/define_the_relationship/
https://www.mangago.me/read-manga/the_man_who_can_t_taste/
https://www.mangago.me/read-manga/walk_on_water/
https://www.mangago.me/read-manga/rix_vanus/

Recommend me some BLs which will break my heart in million of pieces . :D
Maximum trauma
No black flags