Hi  , 

I Want a drama THAT the main leads forced to married each other then .. they get in LOVE . 

Fated to Love- its on my list but I haven't watched it so I can tell you anything other than that is the plot line.
The Princess Hours or Goong- same kinda idea

those are the only ones that come to mind
Bride of the Century - love after engagement
Emergency Couple - ex lovers fall in love again 
King2Hearts - forced to marriage but fall in love
Marriage, Not Dating - same thing

Enjoy !
Sweet 18
Easy Fortune Happy Life
Delightful Girl, Choon Hyang - they get married in the 2nd or 3rd ep, I don't remember but it's very fast.
Creating Destiny (be aware that it has 31 episodes)
Prime Minister and I
If you want to consider a Hong Kong drama then Can't Buy Me Love fits the bill, it's really funny too.

In Super Daddy Yeol they don't get married, but they are kind of forced to live together then later fall in love as well