siempre:

Either way, the Constitution left it to the states to decide and as pointed out about guns, it has not been decided if states are legally obligated to recognize all of each others contracts

Oh, it's been decided already. The Full Faith and Credit clause of the Constitution requires it. However, in states where the majority do not want same sex couples to marry there is enough opposition to keep the marriages unrecognized. Or at least, that will be the case until the Supreme Court steps in. The system of checks and balances works well, but it doesn't work quickly. I expect it will be at least five years, and probably closer to ten, before a case comes before the USSC.