Honestly it's important to remember that for the longest time the Dwarves and Elves ways worked... until they didn't.
Natually they are longer lived so they are going to slower to change in response, which in turn causes things to get worse while they try and adapt to the old changes, and even worse if they make a change that isn't for the better cultural inerta means they have to take the time to undo that change than move to a new one.
In some ways allying with a shorter lived species that can take a few hits from mistakes and bounce back from them in short order might actually be of help to them.
Natually they are longer lived so they are going to slower to change in response, which in turn causes things to get worse while they try and adapt to the old changes, and even worse if they make a change that isn't for the better cultural inerta means they have to take the time to undo that change than move to a new one.
In some ways allying with a shorter lived species that can take a few hits from mistakes and bounce back from them in short order might actually be of help to them.