Actually, this is a federal issue, since the 4th Amendment's Equal Protection clause requires that all people be treated equally, regardless of which state they live in. The fact that the issue is under review by the US Supreme Court at the moment is evidence of this. The Supreme Court has previously ruled that marriage is a fundamental right, and stepped in to outlaw interracial marriages by states via Loving v. Virginia (1967). As a matter of public policy, we don't let each state set their own rules on who can be married when those rules would conflict with the federal Constitution.
Of course, we're discussing a civil marriage license, not a religious wedding ceremony. Churches will always be free to discriminate in who they marry, according to their beliefs. No US court has ever required a Jewish synagogue to perform a Catholic wedding, or a Methodist church to perform a Mormon wedding.
As to the "hate", I agree that this is not a "hate" issue (although some people are truly hateful). Hate is an emotion, and the gov't doesn't regulate emotions. It's probably more accurate to say that someone who believes that gov't should treat different groups of people differently would hold a bigoted position (bigotry being an irrational bias against someone else).