You are in PR-relationship with Lee Dong-wook. You both are co-stars and shoot a rom-com K-drama together. You see each other every day at home and at work. To you it's just a job and a business deal.
The media, the fans and even your co-stars and co-workers think you two are really in love. and inseparable. This will benefit Dong-wook's and your own career, including boosting the hype of your TV-show. The manager and producers hope you two will fall for each other for real during your time together. This would make your relationship easier to sell to the media and fans.
Dong-wook behaves cold and indifferent towards you. Except when you have to pretend to be dating or shoot your scenes. He is not interested in you or this relationship at all. You know he dates another woman in secret, so no matter how you two act as a loving couple in front of the media, fans and the camera, you keep it professional at all times.