You need to figure out the signaling then. It isn't that most people would never settle with a Republican pro-lifer, it's just that being a Republican/pro-lifer is an indicator of other incompatibilities (which usually is a good indicator of other things).
Take for instance you yourself are better off filtering out all the Republican/pro-lifers because of the baggage they'll bring with them.
Usually the signally has evolved to be different. You don't say Republican, you say Libertarian (considering gay rights being one of the topic of difference).
I'm registered as a Republican, and in theory, would rather date a Republican than a Libertarian. In unsurprising news, every woman I have ever dated has been a Democrat, and my wife is a Democrat from a socially democratic country. She will be joining me in voting for Gary Johnson in the upcoming presidential election, but is voting for Hilary in her party's primary.
It's funny, I used to look at the types of signaling you reference when I was dating (do we like the same things, have the same outlook, etc). I have found my greatest happiness with my wife, and the only two signals there I used were her work ethic and intellectual capacity. Well. And she's the hottest woman I've ever seen. All three, and I couldn't wait to put a ring on it.
Take for instance you yourself are better off filtering out all the Republican/pro-lifers because of the baggage they'll bring with them.
Usually the signally has evolved to be different. You don't say Republican, you say Libertarian (considering gay rights being one of the topic of difference).