It's actually incorrect to say that most districts voted for the amendment. A majority of house districts and a majority of senate districts voted against the amendment. But those districts were sometimes mismatched, with suburban districts who voted against the amendment sometimes represented by Republicans, and rural districts who voted for the amendment sometimes represented by Democrats. But if every politician voted for the marriage bill the way their constituents voted for the marriage amendment, the marriage bill would still have passed by a sizable majority.
And for anyone who cites the county numbers, the counties that voted for the amendment only account for 43% of the voters.