There is an established narrative in fantasy fiction and gaming that Elves and Humans cannot relate because one lives so much longer than the other. This is total bullshit. Utter Poppycock!
It's like saying that humans cannot relate to dogs and cats because our pets only live a fraction of our expected lifespan, or that children don't matter because they haven't been around long enough. Okay, for some people this is true, cold bitter people, but for most of us it is poppycock! (And no, I just can't let pass any chance to use the word poppycock! Doh! There I did it again! Poppycock!).
For the most part we exist in our short-term memory. We can project a few days ahead of ourselves. We can easily remember backwards for a couple of hours, but after that all we have is long-term memory. Those memories - our proof of our prior existence - these we need to ask our minds to dredge up. The older they get the more decayed they become, the more questionable their accuracy.
I sometimes think that this is the driving force behind the twenty-year nostalgia cycle, that twenty years is the freshness date on human memories. We celebrate them as one last hurrah to their reality. After twenty years we lose our personal connection to them. They are still there in our heads but the vibrancy is missing, the dialog absent, the impact gone. It is almost as if it all happened to somebody else, except for the fact that we never leave the scene.
My point is that until we find some way of expanding the barriers of time which pen in our mind, we are all pretty much twenty years old. Which is not to say that we all act like a bunch of twenty year olds. We are what are memories tell us to be, which is constantly backed up by the physical state of our bodies. Progeria is a genetic disease that causes rapid aging in those who have it. Take a youngster with progeria, force them to live for two decades as a senior citizen in a retirement home, and while they will be able to tell you their age and logically believe that they are only that old, I would be willing to bet that their psyche would test to be no different from the actual senior citizen surrounding them.
On the flipside, imagine an elf who still has the body of a twenty year old despite having lived for 10,000 years. Considering that the elven brain has the same capacity and limitations as a human one, how do you think that elf would act? There would definitely be some very old memories bouncing around down around the bottom of the corpus callosum, and the idea of having another 10,000 years to live will definitely change the way one plans for the future, but plans are just hopes easily forgotten (unless we saddle ourselves with a constant reminder of them). When the elf's guard is down, when not acting ones age for the expectations of everyone else, that elf will have a personality primarily defined by the last twenty years of experience.
As do we all.