It's not really an easy "problem" to solve though. Civil (ie. government sanctioned) marriage is a social construct that most people want to, and eventually wi

It's not really an easy "problem" to solve though. Civil (ie. government sanctioned) marriage is a social construct that most people want to, and eventually will, enter into. People enter into marriages because they want the legal framework around it. If there were no legal framework around marriage people would have to run around filling out paperwork everywhere setting up their partner as their next-of-kin. There's also currently no non-marriage way to create the same sort of civil partnership that marriage brings, stuff like spousal privilege and unlimited inheritance just to name two. And these are things people want. If all people were interested in was religious marriage or partnership/love/companionship they either wouldn't bother getting married or wouldn't bother registering their religious marriage with the state. Its currently impossible to get government out of marriage without also fundamentally changing our concept of marriage. There's arguments that the "family/marriage" concept is benefited too much in society, and I'd probably agree with that.