That winter the wind blows

Cain and able 

My love eun dong

Missing you 

Come and hug me

Just between lovers 

Or Simply watch any korean melodrama. They're all sad & most have a happy ending. 

https://mydramalist.com/13388-mask (you must watch it, i guarantee this is the best)

kill me heal me

miracle that we met

my ahjussi (but it isn't too clear)

the guest (no romance, horror and friendship)