I find the premise of half-elves (and the relationship between an elf and a human) to be ridiculous on its face. I don't remember who talked about it somewhere that I read... but basically the Human lifespan to an Elf is like a Human's lifespan to their pet dog or cat. You go into this relationship knowing that you are only going to have only a small amount of time (probably like a decade or so) before you lose that creature, and that you are most likely going to "replace" said creature who knows how many times over your life once each of them is gone. So there is a certain detachment you have to have in that relationship, knowing its going to be so short (not to mention the fact that you are quite likely to have three, five, who knows how many more similar attachments like this over the course of your lifetime.)
As a result, I find it exceedingly unlikely just how many Elves across all these game worlds knowingly get into romantic relationships with these Human people who are ostensibly aged like pets... knowing full well the relationships will last only 1/8th of their lives... then having children with those Humans that they know for a fact will only live like maybe a quarter of their lives if they were lucky. All on a numeric scale that is just ridiculious.
I could accept the rarest of occasions where this might happen... where some rare singular Elf just can't help but fall in deep with their Human pet to actually have a romantic relationship with them... but based the sheer number of half-elves that live everywhere in every game setting... Elves apparently are the most sociopathic a-holes ever. Bedding whatever number of Humans they want, knowing they are going to watch them grow old and die... and having multitudes of children with them that they are also going to watch live, grow old, and die numerous times over throughout their 800 year lifespan. And apparently be completely okay with that based on how often these relationships happen across every single game world. Cause it ain't like half-elves are a rare species like Aasimar usually are.
The problem is... we humans just cannot conceive of what living an 800 year life actually would be like. So all this stuff we write about is us treating all these things from the perspective of what we know of Humanity. We don't write Elves like what an 800 year old creature would be or experience... we write them like they were Humans. Elves act like Humans act, even though they would do the same act over 8 entire Humans lifespans for their singular one. Cause we don't understand what any sort of actual reality for that kind of creature could be. The same way the history of the Forgotten Realms can be written as being "over 10,000 years old" and yet we still write it stuck in this perpetual faux-medieval landscape that has not evolved over hundreds of decades. No technical advancement... no magical advancement... just the same thing millenia after millenia after millenia. Because we can't conceive of how else it would be.
And that's exactly why I don't put any stock in the actual necessity of half-elves, nor treat other species within the game as anything more than Humans with Silly Hats. Because that's all we know as humans and we have no way of actually conceiving what it means to truly be "alien" on that sort of scale.