Marriage and the 10th Amendment

The 10th amendment clearly states that, "The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people." To me, this means that the definition of marriage is a state issue. It should be within the state's authority, through our system of representative government, to decide what the state, and its residents, will recognize as marriage. Under DOMA, states are not required to recognize same-gender marriages that would be recognized in states like Connecticut. This is constitutional; everyone in that state is being treated equally. That state, and its Constitution, does not recognize same-gender marriages for anyone. Is it in violation of the 14th amendment for states to have different laws in regards to taxes? New Hampshire doesn't have a state income or sales tax, but North Carolina does. Is this a violation of the 14th amendment, because not everyone is being treated completely equally. It's a matter of opinion, residents decide what they think will be best for their state, marriage laws included.