Im living with Zach and have been for the last 4 months. Up until now, we agreed that I would pay the utilites (exc electric cuz it was so high) until I rented my house out. I now have an extra 850 dollars a month and I asked him what he wanted me to do (pay half of his morgage and the rest of bills or what) He told me to just pay utlities and thats it. His morgage is around 800 dollars .. The utilities equal up to about MAYBe 600 dollars and I get groceries (well tecnically we both do).. Anyways, I dont really know if what we are doing is fair or not. I cant tell. I dont want to be 'using' him. We talked about getting a joint account. I went and opened the account and he has yet to add his name. BTW, this account is only for bills, I will still have my seperate account. 
What else should I do?
What else should I do?