Yes, people do need to take accountability for the partners they choose to date, at least to some extent. And no, this doesn't apply to abusive relationships, that situation is entirely different.
I'm talking about white people who date other white people who are openly racist. I'm talking about "allies" who date other people who are openly homophobic and transphobic. I'm talking about liberal women who date very conservative men. And seeing bigotry as nothing more than a "political issue."
Of course, it's different if your partner lies and actively hides their political views from you. But if your partner is openly voting for people like Trump, openly supporting conservative politicians, openly hating/harming minority groups, then you should leave them. And you should be held accountable if you to choose to stay with someone like that.