The answer, I should think, is that she tends to live as if the Universe consisted only of that which she personally knows. Given her tendency towards narcissism, she seems to view the people around her not as people around her not as people in their own right with hopes, dreams and fears of their own but as ciphers whose motivation seems to be to either ignore or frustrate her. The idea that someone might actually sympathize with her runs counter to her need to feel herself alone, persecuted and suffering like no one ever has before and never will again.
This means that she can't see that there are the rare people who aren't turned off by her constant negativity any more than she can see that the women that she thinks want to steal John away from her would be more sympathetic towards her if she didn't make her mistaken impression obvious. She also can't understand that people who watch her whipsaw being bellowing at her children for nothing and letting her walk all over her when that's the worst thing to do too have opinions of their own any more than she can see that the customers who she got bitchy with because they offended a raw nerve who doesn't have any business pretending to do business took their business to the mall because the clerks at Indigo are friendly.