Offending people

Do you ever offend other people unintentionally, like me?

I try to live a quiet life, not bothering other people.  But other people expect me to behave in a particular way and get very upset at things that don't really concern them.  

A recent example is how I upset me sister, by not inviting her to my graduation ceremony.

Beforehand nothing was mentioned or discussed.  I never had any intention of going to the ceremony.  The idea of getting dressed up and being seen on stage by hundreds of people terrified me.  Since the ceremony was optional I turned down the invitation and the two guest tickets.

A week later I got a very distressed phone call from my sister, trying to invite herself to my ceremony.   She had assumed from the beginning that she would be invited.  

End result was that she was so upset.  I got uninvited to her family Christmas.