My 3yo always shouts "I don't like you" whenever she is angry or not getting what she wants. I know she doesn't mean it but it can be demoralizing at times. Does it happen to you too, and how do you deal with it?

Kids are very simple, if they say they don't like you, it's a behavior problems already, it's better to correct it back and stop them from saying this as it may last forever. When she say she want, not say it's correct to give in, but try to give her something else and tell her, cannot say that again, it'll very hurting to you, explain to her why you don't want get for her and let them know the reason, so they will Not repeat again. They are old enough to know what is going on.