I'll recommend you my personal favourites:
The Classic - a memorable love story
A millionaire's First Love - If you like "A Walk to Remember" you will definetly love this one
Sad Movie- it's indeed a very sad but great movie
My Sassy Girl - the best mix of comedy and romance (I've watched it like 6 times and I still love it)
Two Faces of My Girlfriend - almost as good as My Sassy Girl
...Ing - a sad love story
Seducing Mister Perfect - a funny movie
Wet Dreams 2 - comedy with teenagers
Windstruck - sad yet beautiful
My love - if you like "Love Actually" you will like this one too
Lovers' Concerto - a great drama
There are still more to add, I
love Korean Movies