please check my list before reccomending something. Can be from Taiwan,China,Korea or Japan not from Thailand,Hong kong etc.
Ouroboros
Gap Dong
Tree of Heaven
Wu Xin: The Monster Killer
Pained
Secretly, Greatly

ones you've seen, but others may not have:
Uncontrollably Fond
I feel like this is kind of spoiler-y so I'll make my one suggestion in white font to sort-of hide it: Hong Gil Dong is a goofy period/historical-setting TV show with a sad ending. It's not a hopeless ending but it's definitely a sad one and would fit your recommendation.
I agree with @Knavery. Maybe you should put a warning on the title. :)
I recommend these dramas(also hidden): Cruel City, Moon Lovers: Scarlet Heart Ryeo, and 1 Litre of Tears. 
something happened in Bali
Deep rooted tree
you should look for historical or makjang dramas.
SPOILER:
Six Flying Dragons,
Koizora
1 Litre of Tears
Mimi
Boku no Ita Jikan
Scarlet Heart Ryeo:'(
TBH that's practically almost all historical dramas,at least the one's Iv'e seen:/
My recommendations:

1 Litre of Tears
49 Days
Silence
Guilty, Akuma to Keiyakushita Onna
I'm sorry I love you
Jotei
Kamisama, Mou Sukoshi Dake

Mr. Goodbye
Bridal Mask
Death Note
What Happens to My Family?
Moon Lovers: Scarlet Heart Ryeo
Star of the Universe