Shoeboy’s Law of science fiction series

Any sufficiently lengthy science fiction series will degenerate into sexual wish fulfillment for the book’s author.

The canonical examples of Shoeboy’s Law are the Dune series, which includes such things as Amazons from space enslaving the human race with Tantric sex and the Ringworld series, which pretty much degenerates into the hero having sex with bearded alien women (aka “rishathra“). Other examples include the Foundation series (in which the Asimov stand-in upsets one of the other main characters by having Too Much Sex with the sexually insatiable telepath character) and the Rama series, where the anal beads come out around the third book and one is left wondering how exactly they got into space with the rest of the cast.

Here are some links to wiki entries for the first book or so of each series.

Dune
Ringworld
Foundation
Rama

I will update this with other sci-fi series that suit if it comes up.