Section 3 being thrown out? Dubbed unconstitutional?

This Wednesday Obama had declared that Section three was unjust and is unconstitutional. Section three was apart of Clinton's restriction to marriage. Basically what this will do is make same sex marriages recognizable to the federal government. States can still say that they do not allow this in their boarders, but as long as the United States has liberal states like Iowa same sex marriages will keep on, and the federal government will have to recognize these marriages. Section three to me seems to be unfair. As a person who believes in equal rights for all. I personally believe that this is a step closer to this goal. The education cut had stomp on my hopes with our government, but with what President Obama has said this inflates my hope again.