the female lead doesn't forgive the second male lead for interfering with her relationship with the male lead. I see way too many where they act like total pricks and take advantage of their friendships  because he's in love with the female lead and then once things are all said and done, they are forgiven for their terrible behavior.

Nothing like this?

Well, there are some where the second male lead dies!  That happens pretty often in historical dramas.

I don't think any of these are quite what you're looking for (i.e. dramas where the ML and FL are in a relationship and the SML takes advantage of his close friendship with the FL to interfere with their relationship because he likes the FL), but these dramas do have SMLs who act terribly and are not forgiven:

  • Because This is My First Life - the SML has a fairly minor role and his bad actions towards the FL mostly occur before the ML and FL have any kind of relationship, but he's definitely not forgiven and it's pretty satisfying to see the FL confront him and to know that the ML also holds him accountable
  • Misty - the SML is the FL's ex, not her current friend; he faces pretty severe consequences for his interference with the ML and FL's relationship and he's definitely not forgiven
  • The Princess Wei Young - the SML kind of has a friendship with the FL at one point; he definitely interferes with the ML and FL's relationship and acts terribly; he's not forgiven / faces consequences for his actions

There's Koinaka (but since I dropped it I don't know if she ended forgiving the SL)

The other one I can think is close to what you are looking is Delightful Girl Choon Hyang