O Perfume (2012)

both films are about detectives who fall in love or feel attraction for the main suspect of the investigation, an eventually the real killer, a young woman married to an old rich man.

When Shiho Nishina got worried about her sex life with her husband, her husband proposed to her, "Why don't we go to a couple exchange party?" At first Shiho strongly turned down the idea, but eventually, she gave in because her husband was very persuasive. "We're just going to observe, okay?" Shiho said as she reluctantly agreed to it. Meanwhile, a former diplomat Mr. Kubozuka ran a couple exchange club, "Aquarium," with his wife in their house. At first, Shiho was being very cautious, but gradually, she got attracted to Mr. and Mrs. Kubozuka's charm and finally agreed to exchange couples with them. It seemed that their sex problem had disappeard and they had found happiness, but as it turned out, that was just the beginning of their nightmare...

~~ Adapted from the manga series "Fuufu Enman Recipe: Soredemo Otto wo Aishite Iru" by Koshikawa Tamae and Aoisei

This is same, about adultery but unlike "The scent" which took adultery really lighly, "The World of the married " takes it another level. It shows the reality of the married world, the amount hatred one can have after getting cheated in marraige. The plot is fantastic and is a must watch.

This contains adultery but you won't hate this fact. Rather you would be rooting for them. Searching happiness is every person's right, and this is beautifully potrayed in this series.

Yoshino Michi is 32 years old. She's been married for five years, but hasn't had sex for the last two. It's not as if she doesn't get along with her husband, it's just that the sex part is lacking. It was a bit unexpected, but one night when she when drinking with her colleague, Niina Makoto, she wound up confessing that her marriage had turned sexless. And then, a shocked Niina responded "My marriage is sexless, too," and smiled with a lonely look in his eyes.