That's because "marriage" has never been a "right".
It's always been an obligation, intended to be undertaken by a male and a female prior to engaging in behavior which might be reasonably expected to produce children.
No activity by a homosexual couple can be reasonably be expected to prodduce children.
An obligation, not a right.
“It’s always been an obligation, intended to be undertaken by a male and a female prior to engaging in behavior which might be reasonably expected to produce children.”
Actually, the history of marriage was more of a business deal to secure fortunes or raise status.
Even in the Bible, many of the Old Testament patriarchs had multiple wives and concubines.
And if producing children is what defines marriage, then anyone too old to bear children should be prohibited from getting married and if a couple does not produce children within, say 2 years of getting married, they must divorce.