Unequal finances in relationship?

My gal is terrible with money. I am constantly paying for her and for everything she does and I get nothing in return for it. She says that she is saving up money to pay me back all at once, meanwhile I'm the one going broke. I need to figure out what to do in this situation. I do not want to break up with my gal but she is making it very hard on me financially. Is it wrong to ask for some fairness with finances?