The EU didn't participate in the Brexit campaign because that would have rightfully been seen as undue meddling in internal politics of the UK.

In any case I don't understand what you want us to do? Should the EU grovel before the UK and beg it to return? That won't happen. You guys voted to leave. You can come back if you want but don't expect any red carpets.

It's telling that ten years on it's mainly you Brits still kvetching about this.