Female lead is the "other girl"

Any shows where the female lead is dating a guy probably the second male lead and he has a girlfriend/wife, but then she falls for the male lead?

 russian white bear:

on the way to airport  - both lead were married and fell for each other

nice witch  - fl was married

another miss oh - fl almost married

You misunderstand. I want ones where the female lead is the mistress in the relationship. She's not cheating on someone, she's helping someone else cheat at first. Then she falls in love with the male lead.

Bad Love (she is SML mistress).

• Bad Love
• Black Knight

Try Siyah beyaz ask

It's a turkish series.