I once arranged for an important meeting about my work. It was going to be at my living place. I told my room mate this meeting was going to take place and he asked if he could sit in on it and participate. I said yes, at first, purely out of politeness, then within the day changed my mind about it and said that I would rather him not, that It would change the atmosphere and make it difficult for me to concentrate. An argument then insued. He grew angry with me, saying stuff like that he was being left out, that it was his house too and that I couldn't arrange something without him approving, that I was selfish, etc. etc. It was ridiculous. He was kind of a legitimate nutcase.
Long story short, the meeting was canceled and unable to be rescheduled (person who I was meeting with was difficult to schedule with, then I moved pretty far away).
I am generally overly patient with people. I don't show almost any of what I am really feeling or thinking inside. But this is was such a huge, deliberate blow to my work by someone I considered a friend that it completely shattered my relationship with him and feeling of comfort in that geographic region. I moved out as soon as I could and have not really spoken to him since. The memory of it sends chills through me and a weird squirmy energy through my head.