Delusions are fairly common features of Parkinson’s disease. Some delusions are easily recognised, but others are less well-known and can be missed by health professionals. We describe the case of a female patient with Parkinson’s disease who believed, erroneously, that her partner was being unfaithful; this type of delusion is also called the Othello syndrome. After psychoeducation and the start of clozapine, the delusion faded and the relationship became more peaceful.