If you believe in their faithfulness, make him believe your incredibly busy and try visiting him unannounced at his workplace during the closing hours on an unusual day. You will be in for a shocking surprise.

If you believe in her faithfulness, make her believe that you have so much loads of work to do in your working place and try coming back home or visiting her during your work hours on a highly unexpected day. You will experience a shocking revelation.

Many things can occur during these periods when partners are fully aware of each other's engagements and routines, particularly when they are aware of the precise times they can be expected.