https://www.novelupdates.com/series/my-fiance-is-in-love-with-my-little-sister/ (though there's no yandere male)
I don't had any recommendation but I want to say good novel that been abandoned is more depressing to me.
One night, One day, One year, One lifetime is quite a tearjerker. Also, Quick Transmigration System: Male god come here, is a pretty sad, tho the FL (Bai WeiWei) is a fake white lotus, meaning that she never felt anything about the MLs in each arcs. Still, the endings are really sad in each arcs.
You Shine in the Moonlit Night I Want to Eat Your Pancreas Pain, Pain, Go Away Shuumatsu Nani Shitemasu ka? Isogashii desu ka? Sukutte Moratte Ii desu ka? Ame no Hi no Iris Kamisu Reina wa Koko ni Chiru The Day I Disappeared Tada, Sore Dake de Yokattan desu