What eyeliner do you use?
I use a water proof one by e.l.f. cosmetics (I'm kind of keen on my cosmetics being vegan), and while the applicator is great I really don't like the product. See, I thought getting a water proof one would be good for longevity, but for me, after just an hour or two of wear it starts flaking off.
To be fair, I don't have a primer so that could be the problem.