Republicans are Republicans because they hate Democrats, not because they love the GOP. Trump's insults-first approach to politics catches this mood.I would add that many Democrats I know seem mainly motivated by hatred of evangelical preachers and whining billionaires, rather than affection for the Democratic Party or belief in its platform. And many Americans don't bother to vote because they hate both parties.
The politics of America seem to be mainly about what we hate. Obama caught fire because he offered, instead, something for people to aspire to. But six years of watching him beat his head against the wall of the Republican Congress has left everyone even more cynical.