The *real* issue, quite clearly, is that currently states are allowed to define what 'marriage' means to them.
You are pushing for a FEDERAL GOVT definition that will over-ride that.
To try and dis-incentivize a behavior you do not like.
Seems to be social engineering, pretty clearly.
I don't believe this will *ever* pass. At this point, social conservatives are temporarily in the majority, and even now it doesn't stand a chance.
And that majority is in great jeapordy, because these social conservatives are only in power because of the political conservatives who believed in the 'Contract with America'. The CoA said nothing about gay marriage, or gays in the military, or abortion, or the rest. It was about political conservatism -- govt accountability, lower spending, strong defense and security, etc.
The current R party has abandoned the CoA 'political conservatives', and will lose their majority status unless they reverse their focus. And by pushing these issues, they are only pushing the political conservatives away even more.