The first time you leave the party early because you wanted to, not because you had to, is a quiet kind of growing up.

Most early exits come with a cover story, because wanting to go has never felt like enough of a reason on its own. The shift happens the night you stop manufacturing a curfew you do not have. Your own preference becomes sufficient, which sounds small and is most of the architecture of being an adult.

Try it once soon, with no excuse offered and no apology attached. Say you are heading off, say it was good to see them, then go. Nobody will press you nearly as hard as you expect, and the ones who do are telling you something useful.