Now there’s evidence that the heightened partisanship has — paradoxically — led politically mixed couples to understand each other better than before. Surveys have shown that couples often are confused about how aligned they are: Women underestimate the likelihood that their spouses are voting Democrat, while men overestimate that their spouses are voting Republican. But this election cycle, these gaps are smaller, according to New York Times/Siena College polling in three battleground states.

Although a sizable share of Americans don’t follow current events closely and don’t vote, the Trump presidency has been so polarizing and omnipresent that many voters say it has been all but impossible to avoid politics, even for couples who ordinarily do.

“Before Trump, we rarely talked about politics,” said Bradley Hutchinson, 58, an automotive technician in Glendale, Ariz. That changed in 2016. At the time, his wife, Denise, 64, a manager at a utility, was uncertain about Mr. Trump.

Her views are much stronger now: “I’m voting for him because of what he’s done and what he supports and what he fights for.”