Yes, and not everyone can safely escape such a relationship. Your response comes off as dismissive (I assume unintentionally), but we need to raise awareness and provide support for the shockingly high number of people trapped in relationships like this.
You know that, and I know that! Apparently it’s not common knowledge, otherwise this post wouldn’t even exist.
Frankly it doesn’t matter that the vote is actually secret if the spouse is doubtful of that secrecy. An abused person may vote against their conscience on even the chance of repercussions.
That can only leak which closed primary the person chose to vote in. It could be that some of your neighbors vote tactically for the least-bad Republican in the primary and then vote for the Democrat in the general, especially since you're surrounded by Republicans and may not have a lot of Democrats running for office locally (making their primary uninteresting).