Unless there have been big changes to the tax law under 0bama, being married usually screws you over. That is why it's called the "Marriage Penalty" and the time between the first of the year and April 15th is the busiest time of the year for divorces.
Of course if facts don't make your point valid, ignore them or just make some up.
The "marriage penalty" is a myth for most people.
Married people pay more if both spouses have near-equal, substantial incomes. But statistically, the average "penalty" is less than $1500, hardly enough to give an incentive for divorce.
If one of the spouse is the primary earner, with significantly more income than the other, it's much cheaper taxwise to be able to file jointly. That applies in most cases, and is the main motivation for queers to whine about "marriage".