I would be fine with doing away with legal marriage and just letting people appoint others in contracts. If two people have a kid let them be the legal father and mother, when someone dies they can portion out wealth to their spouse or someone else. Do away with filing married in taxes and make everyone file as a single individual or designate a household.
Basically, do away with divorce and just legally change contracts instead of going through the whole divorce process (which is expensive and time consuming). Don't recognize anything as a "marriage" from the state and let people decide.