I'm looking for something that's similar to Innocent Man where the ML falls for the SFL ( I mean it's Moon Chae-Won, how can he not?) but I want to avoid that clingy drama where the ML still has feelings for the FL. I can work with the revenge plot but I want to avoid the whole nonsense where he would still continue to cover/work with her. It would also be great if the relationship between the ML/SFL develops more than what it had in Innocent Man. 

Apologies if it's not making sense. I just finished that series but it felt me wanting more and to find perhaps, a better written series.

This is quite rare...Moon Chae-Won was the FL actually, not SFL in Innocent Man.

ah. I was under the assumption she was the SFL because the ML focused on the other one for so long which I didn't enjoy so much.

yes as Minoucha   said it is quite rare but still I am posting names I don't  think they will exactly fit your description accurately ML/SFL but please feel free to check out to  see if you can find anything interesting because they all have exact similar story to innocent man like betrayal by FL/revenge by ML and all that stuff.

1-Secret (2013)

2- Kleun Cheewit (2017)

3-Queen of Ambition (2013)

4- Fah Mee Tawan (2020) - ( this one really matches your description perfectly)

5-Hua Jai Sila (2019)

6-Five Fingers (2012)

7-Tempted (2018)