"Discrimination" is a vague word. Is it illegal to discriminate? In general, no (nor would you want to make it so), though there are specific forms of discrimination which are outlawed. But "no discrimination" and "equal protection" are not the same thing. Marriage law discriminates on a lot of different grounds, such as age and blood relationship, and very few people want to do away with those forms of discrimination (which are intended to prevent pedophilia and incest, for example). So the fact that the law discriminates against homosexuals may make it unfair, as I stated, and it may be bad law because of that, as I also stated. But it does not violate equal protection, because individual rights ARE the basis for all rights under the constitution. Group rights, even a group as small as two people, have no basis in the constitution, nor should they. The constitution is not designed to prevent the passage of bad laws, and the fact that you and I agree that this isn't a good law doesn't make it unconstitutional.