We don't live in a world of "should", in the real world of course it is demoralizing and affects the vote turnout.
We all know the US government will back Israel no matter what... and the voters can only punish the incumbent party for doing so.
65% of Democrats don't want to finance Israel. Two thirds of their own party, that's massive!
Voter turnout will continue to fall; D and R parties will continue to lose voters (now down to 30% registered voters each) and the Independents will continue to grow (now up to 40% of voters).
Why? Because our major parties ignore what their constituents actually want, and we can only punish one party every term.
It shouldn't be that way, but it is.