Aye.
People are upset, I get that, that's perfectly fine to acknowledge one's emotions.
Now what?
The next step is reflecting on the failure.

That's how you learn from errors, not just in elections, but literally anything. It's certainly more useful than pretending everything was perfect and there's nothing that could've went differently, that's just defeatism.
Criticizing and reflecting to be more self-aware of flaws and strengths, to grow.

Then you can make new goals and strategies for the future and kick future's butt.