Introvert here, and glad most of my friends and family understand my introvertedness. Yes, spending more than a couple of hours in a party, etc. can be very exhausting for me.
I'm fine spending days on my own.
On top of that, a few years ago I did a Myers-Briggs personality test and found out I'm an INTJ personality...and after seeing some videos about it, it truly identified me far beyond I could have imagined.