“Politics makes strange bedfellows” is an old saying. “Politics makes strange bedfellows and marriage estranged ones” was cited in print in 1903. “Marriage makes stranger bedfellows than any other institution” was cited in the book Strange Bedfellows; My crazy-quilt memoirs, life-maxims and what-not (1930) by Don Herold.
 
New York-born actor and comedian Groucho Marx (1890-1977) was credited with this popular line in 1972:
 
“Politics doesn’t make strange bedfellows—marriage does.”
 
       
Wikipedia: Grocho Marx
Julius Henry “Groucho” Marx (October 2, 1890 – August 19, 1977) was an American comedian and film and television star. He was known as a master of quick wit and is widely considered one of the best comedians of the modern era. His rapid-fire, often impromptu delivery of innuendo-laden patter earned him many admirers and imitators.
 
He made 13 feature films with his siblings the Marx Brothers, of whom he was the third-born. He also had a successful solo career, most notably as the host of the radio and television game show You Bet Your Life.
 
29 September 1903, Augusta (GA) Chronicle, “Reflections of a Bachelor,” pg. 7, col. 5:
Politics makes strange bedfellows and marriage estranged ones. 
 
Google Books
Strange Bedfellows;
My crazy-quilt memoirs, life-maxims and what-not
By Don Herold
New York, NY: Farrar & Rinehart, Inc.
1930
Pg. 4:
The title of this book might seem to have political significance, for we have all heard the old saying “Politics make strange bedfellows.” But there are strange bedfellows in all walks of life—in business, in pleasure, in the arts and sciences, in Pullman cars, in golf foursomes, in church, in college, in our clubs, in travel and even in the home. Marriage makes stranger bedfellows than any other institution.
     
5 February 1972, Burlington (NC) Times_News, “For Valentine’s Day, A Few Revealing Comments on Marriage” by Jan King (Women’s News Service), pg. 11-A, cols. 4-5:
Groucho Marx:“The husband who wants a happy marriage should learn to keep his mouth shut and his checkbook open…Politics doesn’t make strange bedfellows—marriage does.”
 
13 February 1972, Sunday World-Herald (Omaha, NE), “About Love, Marriage” (Women’s News Service), pg. 6-E, col. 1:
Groucho Marx:“The husband who wants a happy marriage should learn to keep his mouth shut and his checkbook open…Politics doesn’t make strange bedfellows—marriage does.”
 
Google Books
The Comic Encyclopedia:
A Library of the Literature and History of Humor Containing Thousands of Gags, Sayings, and Stories
By Evan Esar
Garden City, NY: Doubleday
1978
Pg. 734:
Groucho Marx said, “Politics doesn’t make strange bedfellows — marriage does.”
 
Google Books
The 2,548 Wittiest Things Anybody Ever Said
By Robert Byrne
New York, NY: Touchstone
2012
Pg. ?:
414
Politics doesn’t make strange bedfellows, marriage does. —Groucho Marx (1890-1977)
 
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Groucho Marx: Politics doesn’t make strange bedfellows - marriage does. | #Quotes
11:53 AM - 31 Dec 2015