So reading all this maybe desire is not a gap to be filled, desire is openness, it is a new process, as much biological as collective and political; it is on it that the arrangements of your interiors are made and undone; it is opposed to all layers of organization, that of the organism, but also to organizations of power.
Pleasure is a specific organization for a moment, and it can end desire. Desire disorganizes and rearranges in the face of power and pain; pleasure allows one to find the path of desire in disorientation at a specific moment.
Pleasure is a way for a person to find himself in a process that overflows him, or in a desire that overflows him. It is a way to find an environment that is one's own. But we must not relate desire to the law of the lack, related to pleasure.
The devices of power have an immediate and direct relationship with the body, insofar as they impose an organization on the body, whereas the body must find itself alone in its own reshaping, its own rearrangement, like an eternally radiant surface.
To seek a desire that allows us to follow the depths and guidelines of our environment, without indulging in its hollows. The openings of desire exist in a social environment, and can be inhabited by those in search of pleasure, risking or gaining by lodging there as if entering a loop, a whirlwind, without ever following the line to the end.
Desire is the path to follow in its eternal freedom, escaping from any organization, stratum or hierarchy, the path on which pleasure is placed, risking to end it but allowing, when the path is too big for one to follow, to understand for a moment through these organized means, what was the interest of this so great desire that one started to follow. And there was no lack to be filled in the face of the power of this horizon always updated, binding on its path every soul willing to be bound to it.
There is never an organization, an arrangement, an environment eternally adapted, each one must decide to bind or unbind, to build, deconstruct, rebuild, on the open path.
Pleasure interrupts pain for a moment, desire interrupts pain fully, because finally, it creates totally, a new arrangement, a new environment, step by step, eternally advancing.
It's in more general terms, desire and pleasure at large, but speaking of sex I think it's more like : have sex, but know it could only play one specific part of a bigger whole which wil lead you to the real common orgasm (i.e. the revolution lol), so don't dwell on it.
But, for example, if you have sex because you've been bombarded by ads about something related to it, it can become a prison. Your desires aren't necessarily "your own", the pleasure you seek following those desires, are your end. And even for "real" desires, pleasure can mean the end to those, because you would have found your own way of coping, which is good, because it's a "way for a person to find himself in a process that overflows him", but don't end there. Of course we must undertsand our own bodies, desires, minds, alone and together. We are not all grounded and ready to fight, we all need pleasure in our lives, but it's not what will lead us through. Or will it ?
It's thinking every part of you and us as part of the whole system. Your own desires, your own unconscious mind, is determined by your whole political, social, etc, environment, and it's the heart of the battle, even your own soul is for sale, so you must liberate yourself and not fall into any traps along the way.
Hence the quote "pessimism of the intellect, optimism of the will" is especially relevant : your own mind is in the eye of it all, you must fight within it, you cannot have any illusions.
It might be tangentially linked to some forms of buddhism, as are all the forms of understanding of your own consciousness and unconsciousness along the world, that stuff. Though there it's deeply linked to life under capitalism.