The reality is that same-sex couples could be allowed to engage in the rights associated with marriage. The problem is, however, the courts and politics have a problem with thinking that the two could work separately. Civil Unions have been around for quite some time.
The problem for the Left is Christianity.
In giving the gay community the right to marry they are destroying marriage. In destryoing marriage they are putting another nail in the coffin of Christianity.
By destroying Christianity they destroy the family. In destroying the family they believe that they gain total control of shaping society as they see fit.
Unfortunately it will not work that way. If they finally destroy the family their will be no society their will be anarchy and chaos. The order of society will dissolve and the rule of law will be gone. The law of the jungle will reassert itself.