Financial talk

I live with my fiance and i want to know how far should the financial responsibility go. I do not mind helping out with bills and rent, because i live in the home too. I just want to know is the line being crossed when i am paying the bulk of the bills? He pretty much have a dead end job , and he does not make much money. I feel the little money he brings in should be used to help pay bills, but instead he go out and buy things like video games, ink cartridges, and computer software etc. I try to tell him that these things are not necessities, and our focus should be on paying the bills. He do not understand that buying frivolous things it is digging into my pockets. I feel like i am being taken for granted, because he knows i will pay anything lacking. I know we are in this thing together, and do not mind paying my fair share, but i am getting to the point i don't want to do it anymore.