The phrase, ‘bane of my existence’ is used to refer to anything or anyone who annoys you, or causes you much distress. The phrase is also often used to refer to a person you strongly dislike for whatever reason.
The word ‘bane’ comes from Middle English, or possibly dates as far back as Old English. It comes from the word ‘bana’ which means ‘destroyer’ or ‘murderer.’ The use of the word ‘existence’ refers to your life. Thus, the phrase ‘bane of my existence’ literally means something that destroys your life.
Bane also originally referred to poisonous plants or substances, hence we have English words containing ‘bane’ for some poisonous plants, such as wolfsbane and hensbane.
While the phrase is somewhat archaic, it is still fairly regularly used in modern English. However, it is generally used more lightly than it was probably used in Middle English. You might hear someone say it in an over-the-top, sarcastic way, or in a mock British accent for dramatic effect.
An example of the phrase in modern English would be: “I’m severely allergic to strawberries. Every time I eat them, I break out in hives. They are the bane of my existence.” Another example would be, “Our mailman cracks sexists jokes all the time. He’s the bane of my existence.”
Another way of saying something or someone is the bane of your existence is to say that it is your nemesis or arch enemy. Other synonyms for the word bane include: scourge, curse, and affliction.