That’s out of more than 60 million married couples in the US. Barely here equals about half?
Well, first, married women are not evenly divided. They are more Republican and less Democratic than unmarried men, who are also Republican.
Second, even by the numbers you cite, Democrats aren't coming close to half of the vote among married couples.
Third, you have over 11% of the vote going to third parties. In reality, in 2016 the two-party vote share was just over 94%.
Some of these problems seem to arise from you confusing party affiliation with voting. They're different.