My parents are/were a weird lot. For example, when I was a little girl, my dad would call my mom “Mommy.” This would bring out a jealous rage in me.
“She’s my mommy, not your mommy,” I would pout.
As my parents became seniors, and my dad battled dementia, they fell back into this habit. My mom even referred to Dad as “Daddy” at the hospital, earning some raised eyebrows from the nurses. She defended herself by calling it a term of endearment.
I guess it was to her, especially after taking care of my dad like a child for the past few years. By that point, he was less a husband and more a difficult child who would never grow up.