How do you explain to a slightly autistic 5 year old that no one hates her?

I empathize with you, I do. My grandson will be five in a couple of days and he too is either Autistic or has Asperger's syndrome. Either way, he does the same things such as he'll insist on things which either aren't true or he doesn't understand and he'll do it in a very dramatic way.

Most of the time we simply do what you are doing now, comfort and love him and tell him very casually it's not true. However, for our situation we find it best not to push the subject during the peak moments of his freaking out ( bad term i know but it's late and I simply cannot think of anything else at moment) and we wait to speak to him about it afterwards and usually that is when we get the best results.

I'm sorry, I know I did not really help much or answer your question but I was so compelled to at least respond. Good luck with your niece, truly.

"Explaining" often doesn't work with young kids - many do not have the vocabulary to explain how they feel. It really is quite complicated to understand " I love you but I don't always like your behaviour" Try to correct her behaviour with positive reinforcements. Be lavish with praise when she is well behaved.

Almost all children have this problem at some time. Parents feel hurt when the child says "I hate you" when they mean - I am frustrated that you won't let me do what I want,