Learn English – What are the female and gender-neutral equivalents of ‘henpecked husband’

This practice began round about the time of the feminist movement in the late 20th century(c.1980-c.1990)

Taken from the Free Online Dictionary:

Usage Note: Using she as a generic or gender-neutral singular pronoun is more common than might be expected, given the continuing debate regarding the parallel use of he. In a 1989 article from the Los Angeles Times, for instance, writer Dan Sullivan notes, "What's wrong with reinventing the wheel? Every artist has to do so in her search for the medium that will best express her angle of vision." Alice Walker writes in 1991, "A person's work is her only signature."

Wikipedia notes why:

One response to this (use of generic pronoun he) was an increase in the use of generic she in academic journal

The correct term is spouse:

The term is gender neutral, whereas a male spouse is a husband and a female spouse is a wife.
_{(My emphasis)}

Both members of the marriage are spouses, regardless of sex.

In the context of your table, Spouse 1 / Spouse 2 or Partner 1 / Partner 2 (or A / B) would be perfectly acceptable. Since you've specified Married Date in another column, I doubt anyone would be confused about whether or not they were actually married. There's also probably no harm in simply stating Spouse twice, like you have for Age.