I know a Danny & Sandy who have the same first names as the leads from Grease.
But I think that is the only ‘fictional’ couple I know.
I would guess that these couples might be fairly common in real life:
Rob & Laura (Petrie)
Sam & Diane (Malone and Chambers)
Bob & Emily (Hartley)
Alice & Ralph (Kramden)
George & Louise (Jefferson)
Probably not as common:
Archie & Edith (Bunker)
Scarlett & Rhett (O’Hara and Butler)
Bob & Helen Parr seem likely.
A girl who used to board her horse at the same barn as me had grandparents named Fred and Wilma.
StG
I know a married couple named Luke & Leah.
It rather sickens me.
Fred and Wilma live across the street from me. He joked about it the first time he introduced himself to us.
Not exactly a couple, but some years back my parents already had a cat named Kate when they adopted another cat whose name happened to be Allie.
The reference.
It wasn’t until the third season of Mad Men that I processed that Don and Betty Draper shared first names with my BIL’s parents. I think it took so long because the two couples don’t live on the same planet (even allowing for the fact that one couple is fictional).
Believe it or not, I know a Niles and Daphne.
I know a Nick and Nora.
I’m friends with a couple named Jack and Diane, who have a dog named John and a cat named Cougar…
I used to go to church with Fred and Wilma. Their oldest daughter had red hair.
I went through my 20-year marriage as one half of Charles and Di.
Yes, I know the OP asks for “fictional” rather than “famous”.
I had neighbors called Betty and Al.
While not fictional, my grandparents names were Bonnie and Clyde.
Almost. My parents’ names were Jack and Jean. And when they were dating in high school, everyone called them Jack and Jill.
My grandparents, who both predeceased the television program, were Will & Grace.
When I was growing up, neighbors across the street were Albert & Peg Mundy, rather than Bundy. Albert was known to friends as Bert, though, IIRC, he’s been gone nearly 30 years.
My cousin Lois very, very nearly married a man named Clark but called it off three days before the wedding, which was to be Superman themed. He’s now a stumblebum drunk, so good call on Lois’s part.
I knew a couple whose kids were named Nick and Nora.
Oddly, they were not named after The Thin Man characters.
I just realized last week that I know a couple named Mike & Molly who recently started dating, and are both large people (that’s the plot of the show).
I know a Ross and Rachel.
I knew a “Fred and Wilma” in Indonesia. In the early 1990s, we had neighbors who had two little girls named “Kate and Allie”.