You do realize...PeterD...that superior spiritual purity ...actually enhances the libido...in this way...if I may...umm thank you...it goes like this(hey...Im a story teller...we always try to prolong...we are never alone that way} the joy of spirituality induces a jealousy of the flesh(it wants joy as well)...that is quite powerfull...and of course...the more we resist..'the stronger it becomes...and on and on...so many paradoxes...gots to navigate it...To directly answer the threader...there is a reason to sex...its better...the sex...id est... not to angst over the reason...with that...I prepare for a wonderful day...
EDIT...Ghandi used to sleep with young women so as to test his ability to resist...it is said he was successful at such...I believe he was...just to keep it honest...celibacy of flesh...does...imo...transform...sexual energy into spiritual energy...tho again imo...celibacy of word...may have have even more power...than anything...I have been unable to master that as yet...way too powerful