Equal treatment?

We live in a society where the traditional gender roles have dissipated. Women have increasingly become the breadwinners and men-- stay-home 'Pa's. Except for certain biological differences, such as giving birth, basically today it must be recognized that there are no differences between men and women. The age-old traditional roles prescribed to men and women simply are not relevant, except to our grandparents, who still live in the old age... We can say that our society has become really 'transgender.' If sexism still persists, it is because of competition and prejudice. Why then does our society still stigmatize people who really do not recognize these gender roles, for example homosexuals. Similar to the stigma attached to the victims of AIDS in the 80s and 90s, today that stigma is still strongly attached to the gay people. Homophobia is still a virulent disease inflicting even the most 'liberal' people...

Article 2 of the Universal Declaration of Human Rights stipulates equal treatment for all and Article 16 provides for the right to marry (here). I wonder, if everyone is entitled to the equal protection of the laws, including enjoyment of all Universal rights, and if men and women have the right to marry, then how can we say that by denying the gay people of the right to marry, we are not discriminating on them? Is that equal treatment? We are depriving a minority of a right that we, the majority, have... How acceptable is that?