Got to say I can't believe that's true, but if it is, it means Team Obama is in major danger.
He absolutely can't afford to lose anyone in his base. At the same time I'm sorry but Obama can't afford for more than a second of his time to go to keeping young and left-wing voters. If he doesn't already have them he's already screwed. It's all about moving to the middle if he wants to win and gay marriage is waaay more than a symbolic issue for the middle.