In late 1743, with the success of the Miscellanies, Fielding's situation looked relatively settled. He still travelled the Western Circuit, he had generous patrons, and he also had a new son, Harry. But over the winter all this good fortune was undermined by Charlotte's worsening health. One distraction was provided by Sarah Fielding, whose novel David Simple appeared in May 1744. In a Preface to the second edition, Henry suggested that the form the ‘Moral Tale’, the wanderings of an innocent youth in the city, may have drawn on his Joseph Andrews: in his view the novel's only faults lay in the want of ‘learning’. Both points, understandably, may have piqued his sister: in Familiar Letters of David Simple (1747) she deliberately chose the epistolary style of Henry's rival Richardson, now her close friend, and she began studying Classics with zeal.

Fielding himself contributed five letters to Familiar Letters, including Valentine's praise of true, chaste, romantic married love. By then the theme was poignant, for his beloved Charlotte had died in Bath, in the winter of 1744. Lady Louisa Stuart, granddaughter of Lady Mary Wortley Montagu, later suggested that Henry's grief was compounded with guilt:

Contemporary stories show Fielding as either prostrated or wildly vivacious. These are not necessarily contradictory. He fought to find philosophic calm, asking himself, as he said he always did in a crisis, ‘What would Socrates have done?’, but his work is full of odd mood swings. Only in Tom Jones, written in bursts from 1745 to 1748, did he fully recover his ‘elastic gaiety of spirits’ and resurrect his lost Charlotte as Sophia, independent, spirited, and brimming with health.

After a year Fielding was galvanized into writing again by the Jacobite Rebellion.