Ok so we know that some wizards marry Muggles, which means that at
some point in the relationship there has to be a conversation that goes,
“Honey, I’m a witch. Stop laughing. This is my wand, I send letter by
owls, and can travel in your fireplace.” And for some people, once their
partner gets out their wand and does a spell, they believe it and
adjust. But there has to be some Muggles that NOPED right out of there.

like is there a Department of Breakups inside the Obliviation office
for when things go wrong? Do you have to send a sad little owl to the
Ministry to have your ex’s memories erased after the relationship ends?

Bringing a whole new meaning to Muggle Liaison Office.

Correct me if I’m wrong, but wasn’t this revealed to be Dean Thomas’s backstory? That his Muggle father noped out when he was a baby?

I don’t think he actually noped out–I think he had a “Buh-WHA?” moment, but he stuck with it. Could be wrong, though!

Neither–Dean’s MOTHER was the Muggle, his father was a wizard but was killed by Death Eaters before he could tell Dean’s mother about it. Dean’s mom remarried another Muggle, so Dean grew up having no idea magic existed until he got his Hogwarts letter.

AFAIR the only character with a Muggle dad who noped out is Voldemort.