I'm telling you that the number of opposite sex couples that cannot or do not have children during their marriages, even longterm marriages, outnumber the number of same sex couples who would get married. This is especially true given that the number of those married couples who are childless increases every year. And this doesn't even include those who have to use some other method to have children, including IVF, surrogacy, sperm donation, children from previous marriages, or adoption.
And the fact still remains that the vast majority of people would still remain married to the person they chose to marry and be allowed to do so even if they could not have children with that person. This logically proves that the main purpose of marriage has nothing to do with procreation.