Just 26,765 days -- and counting.That's more than 75 years and it's how long former President Jimmy Carter and his wife, Rosalynn, have been married -- making them the longest married presidential couple.The Carter Center celebrated the milestone Thursday when the couple bested the record held by the late George H.W. Bush and Barbara Bush.And to think it might have turned out differently.When Carter first proposed, Rosalynn rejected him. Why? She had made a promise to her dying father she'd finish college first.As she recounted in her memoir, "First Lady from Plains," the pair grew up three years and three miles apart.There were no girls in town who were her age, so Rosalynn became best friends with Jimmy's younger sister."I thought he was the most handsome young man I had ever seen," she wrote in her memoir.Her father died when she was 12. But she kept her promise. She graduated from Georgia Southwestern College.The pair went on their first date in 1945. They married the following year.He was 21. She was 18."The best thing I ever did was marrying Rosalynn," Carter once said. "That's a pinnacle in my life."Related video: Former President Jimmy Carter celebrates 95th birthdayThat's not to say it's been easy sailing all through. For example, take the time the couple decided to write a book together."It's the worst problem we've ever had since we've been married,"Carter jokingly told CNN at the time.He is now 95. She is 92. Their love story is still going strong.