to charliehall: “”unmarried couples publicly living together””
There are many views that in such cases, assuming they are both Jews, they have made a kiddushim by bi’ah, and she requires a “get” if she ever wants to marry anyone else. The complication is that if you are a “liberal” as to what is required to make a marriage you end up in a situation in which within a few generations most non-frum Jews are safek mamzerim. The “stricter” opinion requires intent to be married by halacha, which means regarding all marriages involving non-frum Jews are void which is very insulting to them but means their children can’t be mamzerim. It’s an ongoing dispute – that has nothing to do with “gay marriage”