I'm looking for dramas where a villain or antagonist ends up with a girl after a redemption arc of sorts.

The Smile has left your eyes => I'd actually recommend you to try this first. It fits  with what you look for. However here it the thing. This is based on a Japanese version that goes into a very ....unique direction that is not used for the kdrama. So the korean version is fine. Thats why you should focus on that one instead and not not he Japanese ;)

Flower of evil
Always - this is a movie
Just Between Lovers

Kidnapping Game - Chinese drama. There is a Japanese remake, but the Chinese one is a lot better and really has the romance aspect super well developed

Burning Ice - this one is very tricky. It is not a romance drama, it is a thriller, but there is a large part focused not he romance between two characters. However this one he starts out good - becomes evil  and then it goes to your direction. 

I'm not sure about redemption arc but they're all trying to compensate FLs in some way and some of them give FL an option to leave them, so maybe: 

Another Miss Oh (ML is the cause of FL's suffering as he scheme FL's fiancee to be convicted as he was mistaken about FL's identity)

Bread, Love and Dreams (ML2 forces FL to marry him using ehm money iirc)

Feast of the Gods (ML is trying to destroy/take-over FL real family's business)

Hotelier (ML is trying to take-over the hotel FL's been working for more than a decade)

Kleun Cheewit (ML is torturing FL physically and verbally because he believed FL is the driver who hit his late fiancee)

Story of Kunning Palace (ML is the one who order FL's death penalty in previous life)

You Are the Best! (ML is using FL to win a bet with ehm a friend/love interest, I kind of forget)