Something light and cute. Slow romance. Happy ending. Something like My girlfriend is a gumiho, Monstar, Smile You.
Since you are asking about dramas with a happy ending I'm going to post it in a different font color. Just highlight it to see.


-My lovely sam soon (2005)
-Delightful girl choon hyang (2005)
-Biscuit teacher star candy (2005)
-Dal ja's spring (2007)
-Protect the boss (2011)
-All about my romance (2013)


All of these are kdrama romantic comedies with happy endings.
I can suggest Japanese drama ' Rich Man Poor Woman'. Slow romance and happy ending and cute couple. I enjoyed watching it :)
I don't have time to search for it right now, but there is a thread titled Happy Endings :)
Flower boy next door! :)
japanaese drama Switch Girl! is super funny, the actor's expressions are so amusing
In time with you http://mydramalist.com/taiwanese-drama/2957/in-time-with-you
Really warm, cute and left me utterly satisfied :P