Support is not turnout. When will the pollsters get it?
Many of those voters may prefer the traditional definition of marriage, but do not think their vote will make any difference. Once the local bureaucracy thinks being PC will keep them in office, it is difficult to stop that train of thought from picking up speed. This happens a lot in my state of California.
On to the judges! (Sarcasm folks)
Romanians did not go to referendum because there was some hidden propositions on the ballot. One of them was that of decriminalize the abuse of power. The actual president of the Romanian Socialist Party and the president of the Representative Chamber recently got 3.5 years prison for abuse of power.
Im quite sure this was calculated, as the opponents guaged the level of support and merely didnt go to the polls - a veto by non-participation.