Okay so as a person who can be very social, talkative, and genuinely enjoys interactions with people.
I am first an introvert. And that means there is a very decent chance any social outings can suddenly sound like a dreadful experience regardless of the company because you just do not have it in you to be interesting to them or interested in them. You just wake up and are like.. nah, not happening. Sure you made a commitment and will push through but that is why we are delighted when the event itself is canceled and we don't have to force ourselves or make an excuse.