system
Given the following post, respond as if you're commenting on Reddit:
human
[40K] So what were relations between Humanity and the Eldar Empire like before 30K and the Fall.

Did they even care that Humans were expanding all over the Galaxy?
gpt
By the 25th millennium the Eldar already had the pleasure cults and decadence that led to the fall, at this point it's very unlikely the Eldar would have concerned themselves with humanity (or anything else) except when the Humans attempted to settle Eldar worlds.

Between the 15th and 25th millennium is more debatable. The Eldar didn't seem to consider humanity a threat (if they had, they were at the height of their power so could have eradicated the Humans), which to me indicates they were already on the path to the fall. They may have been a tad more aggressive with humans, perhaps keeping them off of Necron worlds in addition to Eldar worlds but the fact that Humanity made it that far, certainly indicates a lack of open hostility.