Traditional marriages benefit society by providing ideal environments for creating and raising children that will become productive members of society. To entice these relationships to occur, we as society offer tax and other benefits to married couples. Gay marriage offers no benefit to society, so the tax breaks should be offered to a more specific group.
Tax breaks should be offered to homes where a man and woman, married or not, live together and are actively raising their own, or adopted, children. All current marriages would be grandfathered in. Tax breaks will no longer be granted to those simply getting married.
If traditional marriage is redefined, there is nothing to stop anyone from claiming inequality and proposing their own definition. This proposal solves that.