I share your perspective.
In fact, both of those "terms" (handicapped and affirmative action) required definitions setting out criteria for whom qualified or didn't for the special supports given those statuses.
The same with marriage: it makes sense for the state to set aside that "word" for heterosexual couples. They are of special interest to the state.
I can think of no reason why the state would have a special interest in homosexual couples except for their susceptibility to serious, debilitating disease. For that reason, I'm comfortable with labeling them under the heading of "civil partnership" or something like that.
I do not agree that they should be endowed with government benefits. That is just a heart string pulling method they are using to get people to eventually agree to their marriage and that their relationships are just like hetersexual relationships. Of coarse I do not think government should favor married couples of either type. I think government should stay out of social engineering. If we followed the constitution there would be no way they could redistribute wealth to certain groups. I can not believe people fall for this crap.