Hard to remember anything that has a whole plot based on it but heres some dramas that have this as a part of their plt maybe covered in 2-3 episodes max.
20th Century Boy and Girl - The FL has a crush on the ML brother but its nothing more than that the ML gets a little angry and stops going after her and attends a marriage date with someone else but when he sees the FL again he goes back after her.
Something About 1 Percent They date as a contract for some time after the contract ends they both try to date other people but they realize the still like each other this gets covered in like the last 2 episodes rest of the drama is nothing about it.
Because This is My First Life The second couple has something like this but not the main couple.