According to a new book based on first lady Jill Biden which casts a light on their 47-year romance, the secret to their long marriage is "good sex." "American Woman - The Transformation of the Modern First Lady, from Hillary Clinton to Jill Biden," was authored by New York Times White House correspondent Katie Rogers, which recently came out last week. Rogers wrote that Biden opted out on running for president in 2004, a decision punctuated to aides when Jill Biden entered the room wearing a halter top with the word "NO" scrawled on her stomach. Joe Biden, told a group of supporters that he had little interest in running for president that year saying, "I'd rather be at home making love to my wife while my children are asleep." Rogers wrote that Biden was "frankly totally in love with his wife." According to Rogers, "Joe may have tamped down on his public bedroom declarations (in) winning the presidency, but he has joked to aides that 'good sex' is the key to a lasting and happy marriage, much to his wife's chagrin."

Biden's first wife, Neilia, passed away in a car crash along with their daughter, Naomi, in 1972. In 1975, the pair was set up for a blind date organized by Joe's brother. Two years later in 1977, Joe and Jill tied the knot at the United Nations Chapel in New York. However, it took Jill five proposals to say yes. "I said, ‘Not yet. Not yet. Not yet.’ Because by that time, of course, I had fallen in love with the boys, and I really felt that this marriage had to work. Because they had lost their mom, and I couldn’t have them lose another mother. So I had to be 100 percent sure," Jill told Vogue. "I've been as patient as I know how to be, but this has got my Irish up. Either you decide to marry me or that's it - I'm out. I'm not asking again," Biden said on the fifth try, Rogers writes.