I won't froth, but I won't have dinner with a Republican either. Their last Presidential candidate was deliberately insulting. We're not just talking about a media figure or fringe candidate, but a person they actually voted for. I came to this conclusion before 2016; 2016 merely marks the point where it became so obvious that no reasonable person could deny it.
Even if they didn't pull the lever for him, he was merely the most prominent example of an explicit, deliberate divisiveness that has become party policy. I don't believe that I can constructively discuss the differences between their values and mine in that environment. Indeed, it feels like I'm being deliberately distracted when they try -- "Here, let us rationally discuss the issues, but regardless of what you say I'm going to go back and vote for the most poisonous candidate on offer".
I believe I've put in sufficient effort over the past few decades to say, validly, "It's not me, it's you." Rather than spend their time talking fruitlessly with me, I would rather they spent their time convincing their colleagues that their vilification of me is absurd and unhelpful. They can learn everything they need to know to support that from reading everything else I write; nothing I say specifically to them is going to provide them any insight into why they have become so wrapped up in vitriol.
I feel that every time I have taken a step towards them, they've taken a step further away. So I'm done. I don't believe that's "frothing". I believe that's a rational reaction to the state of things. It's unfortunate, but it would be irrational to continue to do the same things I've always done and expect different results.
ADDENDUM: This applies even without talking politics. It strikes me as tantamount to "Will you dine with me if I promise not to insult you this time?" I don't enjoy talking politics even under better circumstances, in part because the vitriol has gotten so unpleasant that I believe I'm being deliberately driven out. I won't put that aside and pretend that things are OK.