Age Of Youth, Circle, Kill Me Heal Me, Queen In Hyun's Man, Reply series, The Princess Man
"Goblin", "Hospital Ship" (it's good so far), "Shoot My Heart" (a very heartwarming movie) and "Stranger" (didn't like it as much as others did - which is weird because I have enjoyed anything similar in the past - but I mean... its ratings are high so it might be something for you?).
Empress Ki (I'm about halfway through at the moment, and it really has me hooked haha... don't be put off by the no. of episodes, it's worth it. The cast, especially Ha Ji Won and Ji Chang Wook, do an amazing job at playing their roles)

Tunnel (I've heard some mixed reviews about it, but I personally really enjoyed it a lot)
Master - I'm watching this right now and enjoying it!

Save Me - off to a really great start, very impressive and unique drama

Signal - very highly rated, suspenseful drama

My PS Partner - a fun movie if you are in the mood for something lighter, more adult than most Korean movies get
Healer is the one that jumps out at me right away. 

I also personally loved On the way to the airport and I think you totally should give it a shot even though it kind of deals with similar topics to My wife is having an affair. I dropped My wife, too but still finished On the way to the airport. 
One of my favorite actors is in On the Way To the Airport, so it’s definitely on my very high priority list. Glad to hear you liked it! I highly recommend Nobuta wo Produce. A great coming of age story and drama classic.
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(Double posting because MDL is stuck on the previous page if I don't.)
Age of Youth
Chicago Typewriter
Chicago Typewriter! I'm currently watching and it's very good so far.
Cruel City
1 liter of tears(both drama and movie)
"Voice"! It was very interesting and reminded me of "Tunnel" and "Signal" (if you have watched any of those)! :)
Age of Youth, a really good drama with a circle of girlfriends who try to live together - really funny. 
Chicago Typewriter!!
@wooh_wooow
Not sure if the "Age of Youth" recommendation was directed towards me as I have already watched it? And I loved it.. too much (it's one of my favorite dramas, haha). But either way, I agree with you! It's really funny!

@Kar
"Cruel City" - haven't even watched it myself but a lot of people have recommended it to me and I'm also planning to watch it soon! :)