New suggestions that FDR’s affair with doting Lucy Mercer never ended.

In 1931, when Franklin Roosevelt was considering whether he should, and could, run for the presidency, he called in three physicians to advise on his physical capability. They reported that the man who had contracted polio ten years earlier, losing all movement in his legs, was indeed in good health—and, furthermore, that he had “no symptoms of impotentia coeundi.” “In plain English,” writes historian Joseph E. Persico, “he could sustain an erection.”

It is a significant detail for Persico, given the questions he seeks to answer in his new book, “Franklin and Lucy: President Roosevelt, Mrs. Rutherfurd, and the Other Remarkable Women in His Life”: Did he have an ongoing relationship with Lucy Mercer (later Rutherfurd)? Was it sexual? Was she the only one? His answers to each are yes, undoubtedly, and no.

The charming, pretty Lucy was employed by Eleanor Roosevelt as her social secretary in 1913. Five years later, a stricken Eleanor discovered a bundle of love letters from Lucy to her husband—at which point, Eleanor wrote, “the bottom dropped out of my particular world.” She offered Franklin a divorce, but his mother threatened to disinherit him, and his political adviser cautioned that accepting it would destroy his chances of becoming president. FDR returned to his wife, promising that he would never again share the marital bed—or see his lover, who married a man 29 years her senior.

We have long known that Lucy came back into FDR’s life in his White House years (she was with him when he was stricken at Warm Springs). Persico, however, is the first to document, with letters FDR wrote to Lucy between 1925 and 1928, how early Roosevelt began breaking his promise to Eleanor. The contact between Lucy and FDR, he says, was “almost unbroken” for decades: they spoke on the phone often; she visited him 40 to 50 times in the White House, usually under the name “Mrs. Paul Johnson”; she was present at each of his inaugurations, and FDR orchestrated “accidental” meetings while driving through the Virginia countryside. “If the relationship was simply the shared companionship of old friends,” Persico asks, “why all the machinations to conceal it?”

FDR had a host of close female companions, who Persico says were the “oxygen to his soul.” They included his cousin Daisy Suckley, his secretaries Missy LeHand and Grace Tully, and Princess Martha of Norway. Persico speculates about sexual dalliances with some of them, not always convincingly. What is certain, though, is that they all adored him, and he very much liked being adored, flattered and flirted with. He once told a friend that “nothing is more pleasing to the eye than a good-looking lady, more pleasing to the spirit than the company of one.”

What is unfortunate in the telling of the story of FDR’s romances is that it too often becomes a recounting of Eleanor’s supposed inadequacies. The fact that the “stunningly handsome” Franklin had been attracted to a woman with buck teeth and large feet “who never rises above plain” was perplexing to begin with, Persico writes. She was no match to her rival: “Lucy was far more appealing. Her teeth did not protrude, her chin did not recede, as did Eleanor’s. Lucy’s posture was regal while Eleanor’s was stooped. She had a velvety voice … Eleanor’s was high-pitched.”

The more beautiful Lucy appears, the more Eleanor wilts, in this telling. In the months after she discovered the affair, Eleanor had trouble keeping food down. “The acids brought up by the vomiting,” writes Persico, “began to damage her gums, causing her teeth to loosen, spread apart, and protrude even further.”

It is hard not to feel indignant on Eleanor’s behalf as you trawl through the evidence of her husband’s infidelity and need for the admiration of other women—not simply because she is described as physically inferior, but because she is so often cast as a rejected, loveless figure. The Eleanor who strode confidently onto the world stage and overcame her shyness to fight for those who were unable to fight for themselves, to speak against racial bigotry, economic exploitation, discrimination and dispossession is not here. At times, rather, it seems that her transformation is held against her. The book almost reads like a morality tale about politically active women who let the home fires languish. “Franklin Roosevelt’s dilemma,” writes Persico, “was essentially that he was married not simply to a wife, but to a stateswoman … She might be a scold, and a nag, but he could never shut her out completely because he knew she brought him back to his true bearings. [But] a woman so furiously rushing about to right the world’s wrongs, who would shout a warning, an opinion, a criticism over her shoulder while rushing from the White House to storm the next barricade, could not provide the solace for which FDR hungered.”

But what is most interesting about this tale is what these two giants of American history managed to achieve together, despite their shortcomings—and that they somehow negotiated a marriage where they sought succor and sustenance from others, but still believed in each other. They both grew because of that belief, all while navigating the country through depression and war.

So perhaps there are reasons to be thankful for the devoted Lucy Mercer. She never sought to humiliate her lover’s dignified wife. She comforted an extraordinary president when he was lonely and ill. And perhaps the affair allowed Eleanor her independence. As historian Doris Goodwin says, “I have often thought, ‘Thank God for Lucy Mercer because it freed Eleanor and allowed her to find who she was’.” Which must have been truly pleasing to the eye.