A man broke up with his fiancee after phone calls from a "demonic voice" told him she was sleeping around, the jury in a black magic sex trial has been told.

The man said he believed a black magic curse had been placed on the woman he loved and he was "petrified" when he "continuously got calls from these demonic voices".

The man, who cannot be named, was giving evidence in the NSW District Court on Thursday at the Sydney trial of Tony Golossian, 62, Arthur Psichogios, 40, and his wife, Frances Psichogios, 39.

The men have pleaded not guilty to a string of mainly sex charges relating to two women, while the woman has denied eight charges relating to one complainant.

Crown prosecutor Sarah Huggett alleges the complainants were told, and believed, black magic curses were placed on them that would bring illness or death to them or their loved ones.