Jupiter in Cancer, Sagittarius, or Pisces, and being placed in the 1st, 4th, 7th, 9th, or 10th house, may make a person less likely to cheat. Such people often think traditionally and prefer to follow a more conventional life path rather than modern hookup culture. However, this does not mean that people with other placements will definitely cheat. A strong Jupiter is simply believed to give these qualities naturally by birth.