As someone who's leaning more towards the introverted side of the specturm this is just what I do at house parties when my social energy for the day has left me, but it's not socially acceptable to go home yet. The longer the night goes on, the more I'll be in the bathroom. Not because I drink so much, but because it's the place where I'll be guaranteed a few minutes to myself where I don't have to keep pretending that I'm enjoying this.
I'm pretty sure my relatives think I have some sort of horrible digestive issue. I spend like 25% of holiday gatherings in the bathroom. I just need a few minutes of dark, quiet, not having to think about what to say or what expression I should be making.