Arguably the worst manipulation by a supposed protagonist I have ever seen in a drama:
6. Well-Intended Love - ML gains access to and manipulates FL's medical records to trick her into thinking she has cancer and needs a bone marrow transplant, for which he, surprise, is the only match in the donor database. He proceeds to trick her into a contract relationship/marriage agreement in exchange for his bone marrow (which she doesn't need and he will not donate anyway). He actually has her undergo the unnecessary procedure (or at least somehow make her think she did), putting her in the hospital and having to go through weeks or months of recovery and related medical stuff, all so he can get close to her and keep her with him. Also, stalking and plenty of other messed up stuff. Dude never thought to just approach her and ask her out, apparently. Worst part is she forgave him.
There had to be something illegal about all that.