Marriage has never been about granting special status to a relationship.
Whether one considers the religious traditions or the legal framework, marriage is about protecting a biological relationship between a mating pair and to protect the offspring that result from that pair-bond.
Yes, I know it sounds cold to put it this way, but--biologically, anyway--we have one purpose in life, and that is to procreate. Everything else is just window dressing.
Correct; and not just to have the children, but to dedicate them to the God of Abraham and bring them up in the gospels of Jesus Christ.