Greville never married, but had a liaison with Emma Hamilton for several years when she begged for his help after becoming pregnant with Sir Harry Fetherstonhaugh's child in 1782 and he rejected her. Greville took her in on condition that the child, Emma Carew, was fostered out, and Emma Hamilton became his mistress. He later helped to engineer her meeting and subsequent marriage to his uncle Sir William Hamilton, perhaps in an attempt to win his favour and also to clear the way for him (Greville) to finding a wealthy wife.