The Worst Guy Ever (2007)

Ju-yeon and Seong-tae's decade-long best-friendship comes to a crashing halt one night after they sleep together. The shock of doing the deed subsides, reality sets in, and the two decide to get married. But soon after the wedding, each is confronted with a potentially ideal mate: a sexy editor for Seong-tae and an advertising executive for Ju-yeon. After only a few days as husband and wife, they're faced with the difficult decision of whether to stay together or pursue happiness at the risk of ruining their marriage.