>>3615
Isn't Mammon deified money/wealth? If you answer "I meant mammon as a metaphor for anything to be served" then what, can you not lust after your own wife since "the married man is concerned about the affairs of this world, how he can please his wife, and his interests are divided.". Over-interpreting is a trap.
Sexual matters are delicate. Guilt tripping isn't actually as helpful as you might imagine. He is not damning himself by considering, you've pulled that straight out of your arse. If you keep telling people they are evil and sinful and bad and shameful even before they did anything or make up their mind to do something you'll only strengthen the power of sin over them (let's not forget reversed psychology) and take away their hope which will make it easier to sin. You don't know what's in his heart and how to interpret his lust. Maybe he's just yearning for a beautiful woman that would fulfill his sexual desires with acceptance and without shame and that what he imagines a succubus to be so that's why he's fantasizing about them.
What you should advise is for him to take his heart and make it naked before God. If David was honest about his lust for Uriah's wife and asked God's counsel maybe things would turn differently.