Something that is so disagreeable with your
spirit that it feels
like its existence might negate yours.
This goes further than "hate," and implies that you and the object in
question are sworn enemies.
Can be used seriously or, more likely, exaggerated for comedic effect.
Wearing socks with sandals is the bane of my
existence.
The
iPhone's autocorrect is the bane of my existence.
Stephanie's hair is the bane of my existence.