i take it as a race thing. they live too long, have more time, less drive
Great chapter, hopefully he lets his son in the high elves' lands soon
This, I think, is the best explanation for that. Elves live long lives, so there is less drive to quickly find a partner. Which might be a good thing because the elves would quickly outnumber the humans if they did. As will be mentioned later on, the elves are actually much better at the "conquer and control" strategy than humans are, who are forced to live by it (due to them being so weak as a species). Elves are just generally a more peaceful people. But when push comes to shove, they can quickly become very powerful instead. They are being enslaved in the west due to them living isolationist lives and cutting themselves off from the rest of the world, so eventually the world crashes upon them. But once they are prepared, and interact with the outside world, they become a force of reckoning.
There will actually be a chapter of elves forming their own nation in a while, which is pretty great! And also shows just how powerful the elves can truly be once they are aware of the threat of humans and the outside world as a whole.
Plus I don't think elves have less fertility per se, it is more that it takes a little harder for elven babies to be conceived because of how complex the species is. Think of it as the difference between "fertility" of elephants and mice. Mice have a lot more babies, but they also die a lot quicker and are less complex as a species. While Elephants live longer lives and are more powerful.
Hence why half elves like Wynn are possible, due to the human part of them being less complex and thus making it easier for the child to be conceived, even with the racial differences. It is less that the humans are more fertile, it is more that the elves are more complex.
