Gay marriage amendments aren't just about gay marriage. It is about being punitive and unequal towards gays.
A case from Oxford, Ohio where I grew up, shows how is this the case. Miami University of Ohio provides domestic partner health benefits. The domestic partners are not called married. And, about three-quarters of leading universities provide them. But, a recent Ohio gay marriage initiative, passed after the benefits were first provided, may prevent Miami from providing those benefits and a lawsuit has been commenced by a state legislator to force it to drop them. The NPR story I link also gives a good example of who really will be impacted by the suit, in this case a three year old child of a lesbian couple with one mom who is staying at home because of the child's medical issues.