MY Dear Friend
I am trying to explain you about your question ,my dear WORLD is created by GOD for us and we are the main carectors of this world ,because a MAN and a WOMEN ,the two hands of this world and this world wants from us to create beauty on my surface but it is not possible ,while the opposite meaning is available in this world as when we says Pleasure the next says Sorrow, we say sweet other one says sour...etc. So actual pleasure is far away from your FANTASY discussion .
Fantasy is a natural requirement of your body and if you are not fulfil it then your all body system is useless for you while ,you fulfil it ,in some cases ,those persons who are unable to fix it, in their life, they are fulfil their ,this requirement, in the Dreams or EMAILS,Letters or from Cyber Sex.
Now this is not the matter of confusion ,if you are matured,then choose your partner and play that fantasy in live mode and in this way you are not tourchered from your emotions . I am giving you advise that the matter of world is so complicated and changed for each person .So please follow a system of forgetting and, leave all that bitter experiences.
When I or my spouse is getting the age of adultness then naturally he is fulfil his requirements in the dreams but there is a point ,who is educated him for these Fantasy ,perhaps We are faulty there, because we are not creating a distance from our spouse,when we are fulfilling our Fantasy requirement, and the second one's are EMAILS,Letters,Cyber Sex is also take a major part for this. But you can't do for this ,So leave all that thinking and relexed yourself and promise me , you are not going to the above mentioned ares ,because these are the paths of your mentel Death while they lucrate you as a name of FANTASY.
Cheating is called, when you are thinking that a person looted me with the wrong commitments but How is it possible ,you did that without your approvals.So leave it thinking about FANTASY ,because this is a matter of INTERNAL WORLD and only thinker is presented there not you or any other ,and you can't do anything about to control.