The word in the lower right means,"Nice/Good". So the actual message might be "Happy Married Couples Day"... Ironic, isn't it? (Isn't it sad danna-san?)
Not exactly - if you string it together properly, as "イイ夫婦の日", then it becomes "Day for Good Married Couples", without the congratulatory/celebratory tone of "happy __ day".
Married Couples Day
I dunno if this an actual holidaySonFatherMama"Mother..."
As you may know, some Jap. couples refer to each other as Mother/Father(or variants) as terms of endearment.Happy
