Swing

スワッピング・ナイト　危険な戯れ

Also known as Shujin ni Mirare Nagara...

Akemi works part time to support herself and her lazy husband. One day she meets an old friend and the friend's husband. She becomes aggravated during their conversation when the couple suggest that Akemi's husband's irresponsible behavior is justifiable. As her frustration increases, she meets a woman who encourages her to experiment sexually, which in turn leads Akemi to a labyrinth world of sex and swapping.