Grainger’s social circle in Adelaide, where he first lived, included a Mr George Aldridge who owned the Prince Alfred Hotel next door to the government offices where Grainger worked. He became a frequent visitor to the Aldridge family home and in 1880 married 22-year-old Rosa (Rose) Aldridge. On 8 July 1882, Rose gave birth to a son, George Percy Grainger in Melbourne.

The family lived in a brick house in North Brighton, where they employed staff. John Grainger’s business was on a firm footing and their future seemed very positive yet, during their residence in Brighton, Grainger contracted syphilis. And, as so often happened, he passed the then almost incurable disease on to his wife. In 1885 the Graingers moved from Brighton to the New England Hotel in Heidelberg. In a letter to his father, Grainger stated that he overspeculated in mining shares and lost money. This may explain the Graingers’ sudden change in living circumstances.

In 1890, due to health problems and following doctor’s orders, Grainger ceased working and set out for England on the S.S. Oruba. This virtually put an end to an already unhappy marriage and kept him permanently separated from his child. Deck life seemed to agree with him as he regained his health. Grainger returned to Melbourne but stayed briefly and travelled to Adelaide where he had maintained ties with his wife’s family. Without a business partnership or close family to give him direction he lived a transient life in the first half of the 1890s.

By 1915 Grainger was an invalid and was suffering the last stages of tertiary syphilis, while his companion Winifred Falconer nursed him. His son, Percy, sent him £30 a month from New York as neither he nor Falconer had any income. He died a pauper on 13 April 1917 and was buried in an unmarked grave at the Box Hill Cemetery.