Goodbye, In-law
the FL's sister just married the ML's brother. But their siblings suddenly die from a car crash. The mc's get into a fight at the funeral and got into a car crash but they travel back in time when they were classmates, before their siblings met each other. the main characters try to prevent their siblings from meeting so they don't die. FL has her sister's diary to reference when the two meet. But it comes with consequences since the sister has a stalker making more problems. FL and ML also start getting close and clear up misunderstanding that happened in the past of the original timeline.
My Cute Beast!
Contrasting looks and personalities. FL looks cute but has an assertive personality while the ML looks like a gang member but has a sweet personality. Both the FL and the ML like cute things and are in an online group that likes cats. They met each other online but the ML is the only one who knows the FL true identity. The FL thinks that her online friend is a girl and is too shy to meet up with her. FL also recently broke up with her bf because he is hella rich and had a fiance. FL befriends the friance. The ML also receives help from the FL's younger brother but both guys don't know the relationship they have with the FL
See You In My 19th Life