I think, to be fair, there are only two parties. You can only vote for one "package" of policies. Maybe you are a one-issue voter or maybe you weigh all the different positions of the candidates to find the one who aligns most with you.
I don't think it is accurate to say that all the people who voted for Trump approve of any individual policies -- like this one. So they are allowed to be as upset as anyone else about this stuff.