I have this exact same obsession! Whenever something super exciting is coming up I have the obsessive fear that anxiety will ruin it. I also tend to check how I’m feeling to see if I am feeling happy and if one single anxious thought or depressive or flat feeling comes up I tend to beat myself up over it! I generally have the terrifying fear that if I am not happy during this special moment like I am supposed to then it is automatically ruined! I know no one feels happy 24/7 but I generally have this narrow minded idea that you are supposed to feel nothing but euphoria during a special moment.