True.
The biological function of the human reporoductive system, taken as a whole, is for procreation.
True. So what is the pleasurable aspect of intercourse ordered toward, since it comprises a part of the reproductive system?
(Few of us would be here now if the act of intercourse was not pleasurable).
It can be part of reproduction or the pleasure can be an end in of itself. Furthermore, reproduction can occur without pleasure (such as during a rape) so it is clear that pleasure and reproduction are not necessarily linked.