My common law partner and I live in a house that I pay the mortgage?
On a legal level you would need to speak with an attorney for your state. The laws vary too much for any generic answer to suffice. There are great legal differences between Common Law Partner, Common Law Marriage, Traditional Marriage and Civil Unions. In addition to traditional legal estate issues, there is the question as to whether there was ever a written, verbal or implied agreement. Regardless, either of you would have the option to file suit against the other if you did not like how it turned out. and then, you would hate each others guts. Think of it like a pre-nuptial. If its not in writing, its a court battle where the outcome could swing one way or the other at great legal expense. The two of you should find out your legal options and set up everything in writing now while you are still on good terms.