Empress Ki is kind of like that. She becomes the emperor's consort to exact revenge on a lot of bad people. But he just wants her to love him. And the only other one I can think of that might fit the bill is Personal Taste. He doesn't date her for revenge, but he does pretend to be gay, and then be close to her because he needs to live in her house for a certain angle.
Sorry, that's a tough one! I don't think I've watched any dramas where the hero specifically dates someone to get revenge, although I know its a common theme in other romance genres. I'll keep an eye on this thread to see if anyone has any good ones!
