Here is the thing about same-sex marriage: There is a federal law called the Defense of Marriage Act (DOMA) which defines marriage on the federal level as being between one man and one woman. When a state, like New York, makes it legal for same-sex couples to marry those couples are only able to access rights and privileges provided by that state to married couples. However, because of DOMA, they are excluded from 1138 federal rights and privileges that come with legal marriage. So you may have legally married your partner in your home state but, for example, you can not file a joint federal tax return because the federal government does not recognize your marriage.
That is why the next part of the fight for marriage equality has to be overturning DOMA. In the past week two judges in two sates have ruled DOMA unconstitutional.