Suggest Dramas where

The main lead (who loves second female lead) hurts the female lead who loves her a lot. Let it be little light ...may it not be grey or dark drama

Another Miss Oh I think this suit what you look for

Girls' Generation 1979  Female Lead end up with SML but hurted by the other guy because he is in love with her friend

A Gentleman's Dignity There is no second female lead but ML hurts FL's feeling with another woman in first eps

She was Pretty  There is some misunderstandings but ML thinks he likes FL's best friend

Hot Young Bloods It's a movie but you can look at it if you like

Last Cinderella but with a twist: the second female lead is his sister.

Loving never forgetting. 

Fated to Love You

I Have A Lover

Que Sera, Sera

And a lot of thai dramas like: Sud Sai Pan, Sawan Biang (THE worst), Ngao Asoke. 

Maybe...

.. and mostly romcom and light dramas:

• Fight My Way
• Sprout - not really romcom but more of coming of age
• Delightful Girl Chunhyang
• My girl
• goong/Princess hours