I Need Romance 3 also isn't an exact fit, but is somewhat close. The FL looked after the ML when they were kids (on her mother's behalf, and she did not enjoy the work) and he had a crush on her before moving abroad. He returns to Korea as an adult and arranges through her mother to move in with her temporarily. The FL views the ML as an annoying little brother and does not appreciate his advice, affection, or care. He is supportive of her even when she realizes she has feelings for her boss, and they build up an affectionate relationship even as she starts dating the SML. He is very patient, but ultimately realizes that she is going to keep taking him for granted, so he moves out, telling her she has to choose, and ultimately she does.
