The solution is simple, as it is for gay marriage. Marriage is not recognized by the state/government.

Yep. At the very least, just make everything a civil union that any two consenting adults can enter into. Religious people can still get “married”, it just has nothing to do with the government.

Why limit it to two? I say allow as many people in there as someone wants. It’s mostly for rights to visits in the hospital, parent’s rights, and stuff like that.