Shitty relatives cannot be persuaded. That's why they're shitty relatives.

From this week's Savage Love (emphasis mine):

Perhaps you're not the best person to ask, being a cis white man, but as a queer woman of color, the election had an extremely detrimental effect on my relationships with my white partners. I love and care for them, but looking at those results has me wondering why the fuck they didn't do better in reaching out to their shitty relatives? I'm sick of living at the whim of white America. I'm aware this is the blame stage of processing, but it's left me unable to orgasm with my white partners. I'm really struggling with what Trump means for me and others who look like me. I know my queer white partners aren't exempt from the ramifications of this, but I wish they had done better. Respond however you like.

The thing about shitty relatives is they cannot be effectively reached out to. If they could be effectively reached out to, we wouldn't know them as shitty relatives because they would have been effectively reached out to (and therefore ceased to be shitty) long before we became politically aware.

Don't get me wrong, I'm not suggesting that LW should continue to have sex with people she doesn't want to have sex with, regardless of the reason. (And Dan Savage also stresses this point in his answer.) If recent political events have brought LW to the realization that she's only interested in partners who can effectively persuade their relatives towards acceptable politics (or whose relatives all had acceptable politics to start with), that is entirely her prerogative.

However, my point here today is that some people cannot be effectively reached out to. (Can you? Could a straight white cis man* effectively reach out to you and change your vote?)  And if your partners' shitty relatives were people who could be effectively reached out to, they would have been effectively reached out to long before their relative's partners became aware of them, and therefore wouldn't have fallen under your mental category of "shitty relatives" in the first place.  In a world where there are people who cannot be persuaded on a particular point, I don't think failing to persuade should be seen as insufficient diligence.

*I didn't learn about the English order of adjectives until well into my translation career - and learned about its existence from my Francophone colleagues! But I'm still struggling to figure out what the order of adjectives should be in the phrase "straight white cis man". LW lands on "cis white man", which is counterintuitive to me, but I can't objectively assess which is right/wrong/better/worse.