OK, I'll jump in this pool, I'll even keep all my clothes on if I have to...
Coming from a place of recent celibacy, I would observe that libido and Qui or Prana are nearly equivalent. And even though Freud was wrong about almost everything else, we need to credit him with starting this thread, which was absent from Western civilization until a mere 100 years ago, or so.
The topic itself was taboo until then. Those mid-Europeans were so uptight!
I think a lack of libido indicates a deficiency of Qui, or a Chakra blockage, or a hormonal or neurobiological imbalance, however you choose to look at it. On the other hand, to manifest sexual behavior is an entirely optional part of the process. I believe it is true that some the most evolved and enlightened masters have an abundance of Qui but remain celibate. At least some of them do, but then many don't, and some aren't even upfront about it.
If it's just orgasm one seeks, that can be accomplished quite nicely without involving another soul. That would seem preferable to "fucking". Or am I touching I another taboo here? I haven't heard much discussion of (and it's even hard to render into print) *masturbation* on this thread.
Can masturbation be "sacred sex"? Can it NOT be sacred?
Does it cause blindness? At least its not contagious. But then there IS that biological imperative to reproduce, which persists even after sterilization, but does seem to wane with age. And there is a certain thrill in risky behavior, which can energize any sexual encounter. Some people even arrange enactments of such scenarios, as to experience some of the thrill with none of the risk, but that doesn't seem logical to me. Can you fool your brain that easily into secreting more dopamine, and double your pleasure?
This link has a few lackluster photos of functional MRI of the female brain during orgasm: Scribd and click on the 2nd link on the left side. Ignore the dribble in the middle, which I didn't bother to read (but if YOU do, and it's any good, let me know). These images are not very exciting to look at. And the neurobiological commentary comprising the actual published article is most charitably described as "primitive". Maybe if they colorized the neuroimage it would help. I'll search for a better neuroimaging site and post it later on, if anyone shows any interest. Everyone else around here is too busy getting laid.
Jeffrey/Yubajeff