When she tells you, she hates you, what's your typical reaction?
I've had the hate word, tossed out a handful of times, by pretty much all three, at various ages. "Sorry you feel that way, but I love you." And, then, ignore it, completely. As in, discussion over. 6 year olds, have their own level of irrationality. Can't rationalize with irrational moments. Only state your support, your truth and mix with a little compassion. Wearing yourself out over it, does no one any good.