Friends and family should come first and politics, second.
But how often do we hear about friends or family members who become to cold to one another over political disagreements? Fathers who rarely speak to their sons or daughters because of who they voted for? Siblings who stop communicating over some political argument? Best friends who aren’t anymore because of a philosophical difference? People who unfriend you on Facebook (actual friends, not just online passersby) merely because there’s a disagreement of some sort?
Politicians can definitely do serious damage, but politics itself is almost always temporary. If you have a son or a daughter, surely that relationship is more important than whether they voted for Bill Clinton or Bob Dole in 1996. If you have a brother or sister, that relationship is certainly more important than their opinion on climate change or Obamacare.
Shouldn’t your best friend be more important than even the best candidate?
I'm somewhere on the right politically -- with my own peculiar mixture of conservatism and libertarianism -- but a lot of people I know are on the left. Fort some reason, most of the women I've been close to have been liberal or at least liberalish. So to keep friendships healthy, it's necessary to keep politics in perspective. What you think or believe isn't all that important in the long run. Who you are and what you do are.
Sometimes it's a matter of arguing vigorously but politely and respectfully. Sometimes it's a matter of knowing when not to argue. That's easier for me than you might think. By the time I'm done with work, I'm usually so sick of politics that I don't mind letting somebody else's obviously loony opinion slide right by without rebuttal.