When and why did politics factor into dating?

Inspired from a comment I saw today.

In my 20s, and 30s even, no one gave a shit about politics when it came to dating. No one probably gave a shit about politics in general, but now you literally see on dating apps and hear from friends someone will not date somebody that's a conservative or a liberal or whatever, my parents who are both deceased , I have no idea who they voted for, same for grandparents, aunts a uncles etc. So when and why did politics become a factor in dating someone?

When and why did politics factor into dating?
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