Well you might change how you address your spouse when you've having sex vs, say, you both work together and when you're in a business meeting. But I'm asking mainly like as follows:
5th episode of new anime adaptation of light novel series My Stepmom's Daughter Is My Ex aka Mamahaha no Tsurego ga Motokano datta:
Widow Mineaki, father of male protagonist Mizuto, has recently married divorcee Yuni, mother of female protagonist Yume.
In S01E01: Yuni addresses Mineaki as Mineaki-san.
(slightly NSFW)
In S01E05: Yuni addresses Mineaki as Mine-kun after Yume and Mizuto give Yuni a mother's day present.
The only relevant difference I see here is that Yuni knows Yume and Mizuto are around for S01E05. (In S01E01, Yuni doesn't necessarily know that Yume and Mizuto are on the 1st floor of the house.)
Question: What's up with this change?
Guess 1: When children are around spouses might address each other as even like mom and dad eg in Takagi-san
Nishikata addresses Takagi
as お母さん (okaasan). But idk is it a Japanese thing to change from 1st name-san to nickname-kun when your kids are around?
Guess 2: Or is it maybe the spouses have gotten closer or something in the 4 episodes? (I think their marriage was whirlwind, but I imagine the space between the 4 episodes is at most 2 months.)
Maybe related: Spy x Family: Why does Yor call Loid as Loid-san when with others?
