I do not support the notion that a relationship (whether formalised or not) between homosexuals is equivalent or can be equivalent to marriage.
Marriage has a traditional meaning and function which, even in past cultures where homosexuality was virtually a given within the society, explicitly differs from homosexual relationships. To equate "gay marriage" with "enlightenment" or "coming up with" or "doing away with discrimination" is, in my view, a gross misperception (and certainly a gross effort at misdirection). It has some similarity with insisting that it's discrimination against jelly trifle not to allow it to be called pavlova, or demanding that mushrooms be allowed to be marketed as strawberries, because not allowing them to be so called would be discrimination.
If a man and man wish to live their lives together, or a woman and woman wish to live their lives together, in a sexual relationship, they're not being stopped - but it is almost unbelievably offensive to the very meaning of marriage in all its historical, traditional, societal, cultural and familial aspects to insist that its meaning be stripped and reworked so that it no longer means what it did mean, just so that it can then be applied as an umbrella term to ALL sexual relationships between adults consisting of a vow to live their lives together. That is not the meaning of marriage. Marriage is a far more specific term, and historical texts from every culture with which I'm familiar and have studied spell this out quite explicitly.
I don't apologise for this view, and I see nothing discriminatory in it. We have vocabulary (and dictionaries to render meaning of words) BECAUSE there are differences between things, notions, behaviours, ideas, objects, relationships, etc. This is not an amorphous world. And I object to the outrageous misuse of the very real concept of discrimination by its incorrect application to a recognition of distinct meaning and distinct differences in meaning and purpose and historical validity.