I've been in the sitch where I had more $$ from job than H and I almost think that it may be more of a pride thing(even for women, though prob more huge for men) that she wants to cover as much of the bill as possible. She's not doing so well financially, it is a sore spot- a "see- look I AM doing allright for myself" kind of thing, intertwined with the issue of her starting her own business that she felt unsupported in initially kind of thing.. Like it's her showing her independence and trying to feel good about herself. I'd say humor her, go along with it and keep it. Think that if you return it, may make her feel bad, that she needs a hand out- reinforcing that you are not on the same level moneywise- and that you are thinking she needs money b/c her business is not doing well. Common thing for people to not want to feel like a failure, or feel like they aren't measuring up if they need help moneywise. If you keep it, and act like you've just been helping a little and you assume her help on this- it will put you more on the same level with her. Keep looking for low-cost or free things to do for her and connect to her through...too. Being on the page along with her that she is defining, is going to keep taking you steps up on the way!
Master the self-fulfilling prophecy.. Act 'as if' it's going to happen and make it be!!