The dinner where he admitted the affair was so painful that I must have blanked it out.
go in one ear and out the other
informal
He told me his name, but I'm afraid it went in one ear and out the other.
Antonym and example
remember
I'm quite good at remembering names.
Go to the thesaurus article about these synonyms and antonyms of your mind is a blank/goes blank.
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If you forget something, you are unable to remember it.