Here are some examples of (historical) dramas that made me cry really hard. Somehow here k-dramas are a little less about romance , but with strong friendship and family themes and I found the OST more melodramatic. On the other hand c-dramas here have more romance and the OST is more nostalgic.
k-dramas:
Worrier Baek Dong Soo ( yes, after watching this I can cry just by hearing the music)
Chuno
Mr Sunshine
My Country New Age ( OST is a bit heavy )
c-dramas
Bloody Romance
Goodbye my Princess
Royal Nirvana