sore subject

Translations
болезненная тема
Let's not bring up that sore subject again.
Давайте не будем снова поднимать эту болезненную тему.
Definitions
A sore subject refers to a topic or issue that is sensitive or painful for someone, often because it evokes strong emotions or past experiences that are difficult to discuss.
Words
subject

noun
предмет
sore

adjective
больной