We all loved the romance... and bickering... between Lucy and Ricky Ricardo on I Love Lucy. But they weren't the only couple on the series who kept us laughing!

William Frawley, who played Fred Mertz, and Vivian Vance, who played his wife, Ethel, portrayed such a believable couple that many fans thought they were married in real life, too.

In fact, according to a 1955 interview with the Daily News, Frawley said fans would often approach him to ask about his on-screen wife. Some would ask, "Where's Ethel?" while others would tell him, "Give our love to your wife."

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"They believe Vivian Vance who plays Ethel Mertz is my wife and it wouldn't do any good to disillusion them," Frawley said. "They'd never believe me anyway."

For Lucille Ball, the show's star, creating that convincing dynamic was intentional. Although Ball and her real-life husband, Desi Arnaz, brought their own chemistry to the screen as Lucy and Ricky, she wanted Fred and Ethel to feel just as authentic.

"That's why we picked Bill Frawley and Vivian Vance," Ball said. "They look and act like people you'd meet every day."

For Vance, however, the confusion could get embarrassing. She was married to actor Phil Ober in real life, and fans sometimes mistook Frawley for her husband when she was out with Ober. 

"The women give me suspicious looks as if they've caught me stepping out," Vance said. "I can't always stop and tell them that Phil is my real husband."

While Fred and Ethel's marriage was fictional, the pair's ability to sell the relationship was no laughing matter. Their performances helped make them an essential part of I Love Lucy, which ran for six seasons from 1951 to 1957.

Ball certainly appreciated what her co-stars brought to the show.

"How about that pair of cuties!" Ball exclaimed. "We sure couldn't put on this show without them."

Fred and Ethel may not have been married off-screen, but they made television history together.