female mc and male(not mc) love each other but married to MAIN male character

Is there any k-drama where the two people love each other but due to some reason the female mc need married to the male main character. as the story goes, the female fall in love with the one she married to. 

I have seen this before but can't remember the name...even so, I need this kind of story

excuse me for my English 

Siege in Fog mebbe?? What country?? :)