Which of yuri have you read that are sad and dark , can you recommend a few
The dark and sad yuri by excellence to me is Vengeance, but I can't recommend any other 'cause I try to avoid them.
http://www.mangago.zone/read-manga/living_will/
http://www.mangago.zone/read-manga/white_angels_have_no_wings/
http://www.mangago.zone/read-manga/white_angels_have_no_rest/
http://www.mangago.zone/read-manga/getting_to_know_grace/
http://www.mangago.zone/read-manga/ghosts_of_greywoods/
http://www.mangago.zone/read-manga/girl_in_a_cage/
the last one is kind of a stretch but these are the few i've read that fit what your looking for. hope it helps(●￣(ｴ)￣●)
Omg thank you soo muchヾ(☆▽☆)
Aahh.... Vengeance broke me so hard ╥﹏╥
It's funny, please let it be light, I'm tired of dark and sad plot in yuri stories :(