Call it a flapjack for all of mine...
Where we differ (perhaps) is that our shared value that everyone deserves such a relationship necessarily means that everyone should have the right to marry. I see "marriage" and "committed relationship" as two distinct things
My point is that two people in love who publicly and ostensibly permanently define their relationship, should have exactly equal rights and liabilities with respect to family identity, property, and tax laws.
If you want to make the claim that marriage is a religious function, then remove all legal power from it; it's the same as going to church with your whatever. Put the family breaks in a civil relationship. Which the clergy already have the power to do. They require marriage licenses and such. They are doing a civil ceremony anyway.
Treat them equally and I'm happy. Everybody should be able to pick who they are happy with and not be penalized if Mrs. Grundy doesn't like it.