Discovery of Romance - they broke up in the past but meet again after a few years and has to work with eachother
Missing you - when they were young something horrible happens and they got separated. He never stops searching for her but when she returns...
Emergency Couple - a rich guy marries a poor girl, the marriage last just 2 years, they get divorced - years later they meet again at their workplace
A little different but maybe also your taste:
Legend of the Blue Sea - Fantasy story about a couple that loves each other in a past life and meet again now