Take a step back and consider how hardened the divide is between “the two sides”. It should have never come that far, how are you gonna keep national unity in a situation like that!? Are there other first world countries that are that divided?
(The UK’s a bit of an oddity here in that it’s _kind_ of a multiparty state for historical reasons, but doesn’t really have the right type of electoral system to support a multiparty system.)
Half of the population benefits from the status quo while the other suffers. It is hard to tell whose fault it is, if this question even matters.