I can only speak for myself, but there are plenty of times when the plans sound great in theory, a few days/weeks ahead of the thing. But then when the thing is imminent, that excitement turns to anxiety. It usually has nothing to do with not wanting to do the thing or see the people, but some more gut-level aversion to having your time pre-committed on a day where your body feels the need to just chill or recharge your social battery.