Responses
FL was 11 when she died
it's stated that she was 12, means 12 is her korean age, korean age is one year older than real age (it's just korean culture) so she was actually 11... ML was 3 years younger, so he was 8 when she died in that accident
If she got immediately reborn after that accident, then the age gap should be 8 years

How much older is the ML than the FL? Ten years? At least they didn’t meet again while she was in Middle school or something