ive recently moved in with my gf. She has two dc from a previous relationship. I will be contributing enough money to cover her bills and rent (we have already agreed to this, she would not have let me move in otherwise and hers is cheaper than when I was renting alone) but she now wants me to pay the weekly grocery shop too. This leaves her with more or less her full wage + money from ex for children. When ive said to take the money out of what I give her, she says that I eat a lot more than her and her kids and that its only 'fair'. She said she will save her wage for holidays for all of us so that I dont need to contribute when we go away. Is she taking the piss out of me or is this fair