What is bane of my existence?

The phrase "bane of my existence" is an idiomatic expression used to describe something or someone that causes a lot of trouble, annoyance, or irritation in one's life. It essentially refers to a major source of frustration or distress. The word "bane" historically means something that causes death or destruction, but in modern usage, it has softened to imply nuisance or torment. People often use this phrase humorously or hyperbolically to emphasize how much something bothers them.