I'm forgetting my wife's name?
When I talk to my wife, I don't call her by first name. What do I say, then? Maybe nothing. Or when I want to draw her attention, I say "Ne-e" or "Oi." I was once asked by an English speaker what these Japanese words literally mean. He was surprised when I told him that they mean "Hey" in English. He said he would be murdered by his wife if he said it to her. It isn't the case in Japan, because my wife also say "Hey" to me.
Some husbands call their wives by first names. And so do some wives. But most couples like us, who don't have any other family members, do not call each other by first names, because there is no need to show which person you are talking to.
Then what about couples who have kids? As soon as a baby is born, a husband starts to be called "Papa" by his wife, and a wife is called "Mama" by her husband. A conversation in a family will be like this:
Husband: Where are my glasses?
Daughter: I don't know, Papa. Mama, Papa is looking for his glasses.
Husband: Do you know where they are, Mama?
Wife: You are wearing them, Papa.
Husband: Oh, I didn't notice. Thank you, Mama.
Daughter: Old age, Papa?
These ways of calling each other are quite normal in Japan, even when they are alone, not with their kids.
Husband: Mama, how are Kenta's school grades?
Wife: Not very good. Will you tell him to study harder, Papa?
Since I am not used to calling my wife by first name(Mariko), I have a strong anxiety about the last day of my life. When I am dying, what if I say, not "I love you, Mariko" but "Hey, I love you"?