Hi everyone,
Japan makes some wonderful slice of life dramas focussing on women in their late 20s/early 30s.  For example Hirugao, Renai Jidai and Last Cinderella. However, I'm studying Korean and I was hoping that someone could recommend me some nice K-dramas that fit this genre.

So no high-school love triangles, fantasy, body-swap, girls pretending to be boys to chase their dream-man or dramatic music on cue before throwing water in someone's face :P
Not necessarily affairs, but indeed dramas that don't focus on teenagers or are overly cliche.
Here are some amazing Kdramas where the leads are mature and the storylines are not cliche:
1. That's Okay, It's Love
2. My Master's Sun
3. Good Doctor
4. Another Oh Hae Young/ Another Miss Oh
5. Marriage, Not Dating
6. Descendants of the Sun
7.Oh My Venus
8. Protect The Boss
9. The Bridal Mask
10. Queen In Hyun's Man
11. Chicago Typewriter
12. Jealousy Incarnate
13. Marriage Contract
14. That Winter, The Wind Blows
15. Heart to Heart
16. Lucky Romance
17. My Lovely Sam Soon
18. I Need Romance 3
19. Witch's Romance
20. Kill Me, Heal Me

I also recommend the Korean Movies 'Wonderful Nightmare' 'Always' and 'The Beauty Inside' and Japanese drama 'From Five to Nine' if you haven't seen it yet :)

Hope this helps!!
Thank you all for the replies, I've got a lot to check out! :D

Mature Leads:

That Winter, the Wind Blows (so good the script became a book) 

Dolce Vita (Korean Japanese crossover based on Love Letter, this movie is the closest to Hirugao (2014), affair subject)

A Good Day to Have an Affair (2007 film) 

Jealousy Incarnate (Light hearted romcom career driven woman)

The Producer (I worked in the film industry, so I think this movie was hilarious)

You will love Because this is My First Life


Slice of life with a mature setting