FL obsessed with keeping former love's memory alive and can't move on

The FL has a past love and something special happened between them.  She's now falling for the ML, but her obsession with this past love is causing problems for their relationship. Maybe the past love comes back, but in the end she finally lets go and focuses fully on the ML.

Falling for innocence. The main premise is kind what you’ve asked for. I liked it very much, even if you have too many trops, but it’s nice.

I know, its kinda old, but I would definitely put here Family's Honor 

Who Are You (2013)