If your gut says go home, go. The party will be fine without you.

That feeling of wanting to leave is usually assembled from small things you noticed without putting them into words: who arrived, how people are drinking, the way the room has turned. It does not need to justify itself to be worth following. Staying to avoid seeming dull has a worse record than leaving early. Nothing that happens after you go will have needed you there.

Decide your exit before you arrive: how you are getting home and who you can text. Then leave when you want to, without working the room first. Saying you are heading off is a complete sentence.