To brood over something; to have a persistent feeling of resentment or worry that one cannot forget.
耿耿有心事的样子。不能忘怀，牵萦于心。
《诗经·邶风·柏舟》耿耿不寐，如有隐忧。”
She still broods over the argument they had years ago.
Learn the next connected idiom: 耿耿于怀 (gěng gěng yú huái) → 怀恨在心 (huái hèn zài xīn)
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