Any where the FL gets amnesia and forgets her love for the ML? The SML is either someone from her past that she loved and now loves again because of the amnesia OR the SML uses the amnesia to his advantage to make her fall for him over the ML. Either she falls for the ML again or remembers.
I think "I have a lover" is the drama you're looking for.
The SML loved the FL's twin sister in the past and when he saw the FL (who lost her memory) he mistakes her with the twin sister and yeah the FL falls in love for the ML again.