ntr (???) maybe ?

NTR as in Netorare / affairs / cheating? There are a few:

• On the Way to the Airport - this is the only one I've seen where the affair is between the leads and is more or less the main focus of the drama, although it doesn't feel like a typical affair story
• Secret Love Affair (I haven't seen this one)
• My Mister - the ML's wife has an affair with his superior at work; the ML and FL have a complicated relationship that borders on an affair, but not really
• Misty - the affair is sort of forced and between the FL and SML
• Suspicious Partner - the leads both have SOs who cheat on them

Secret Love Affair is really good- FL has an affair with her student. Husband sucks so there is no need to feel bad for him.

A Man and A Woman- FL and ML have difficulties with their kids and meet because of it but both are married (movie)

Anata no Koto wa Sore Hodo- The only people not having an affair if, I remember correctly, are the people getting cheated on.

+1 Misty- I highly recommend this one

Boku no Yabai Tsuma- The ML cheats on his wife and the story takes off from there

Hirugao- Bored housewives cheating on their husbands. One has been doing it for a while and she teachers another who is a newbie.

Mistress- One of the ladies cheats on her hubby while another lady sleeps with a married man. Not really the main focus of the story but it does play a part.

There are cheating plots in Asian dramas, but NTR doesnt exist outside of hentai. NTR can have cheating in it, but cheating doesn't equal NTR because there's more too it than that.

 ShotaSidePart:

Learn something new everyday

People tend to overuse/misuse the term. Its become such an easy term to use to broadstroke anything involved with romance that isn't pure fluff.