This blinds her to the fact that she comes across as an irritating nitwit who can't be grateful for the blessings in her life. It never occurs to Elly to understand what the words that come out of her mouth sound like to others at the best of times so when she's in one of her trademark "Don't tell ME how good I have it" moods, the insensitivity is doubled.
It also blinds her as to the reason why people want to celebrate her milestones. It eventually baffles her that people are confused and horrified that she doesn't want a fiftieth birthday because she doesn't want to admit that social occasions are as much for the people celebrating as the one celebrated. She sees people telling her she's old and useless. We see people glad that a friend is still alive. We're right. She isn't.