I can't be around happy people...I have nothing in common with them and I can't relate; I don't remember what it feels to be happy. Being around happy people makes me want to run out of the room.
Part of it is my family...I have two cousins who live nearby who I was very close to (past tense, mostly due to them growing up and going to college, etc). One married a great guy (her first boyfriend) after college, got a great job right away, new car, just bought a house, and got a new dog. I cannot be around this part of my family.
Their mother, my aunt, is my mother's sister, and it's just impossible to see them all so amazingly "normal." Like how could everything go so wrong with my mother (she was very sick her whole life with MS and died 5 years ago, and my dad loved her more than can be put into words and now he still doesn't know what to do with himself...he told me he never wanted children, so I am just a footnote to their love story. She was the one who wanted a child.) and then my aunt gets this happy, wonderful life while my mother gets crap for a life. So yeah, I am angry...but I think it would be weird if I was just passively happy for them...I want them to be happy but they can do it without me around.