The issue is not the money. Money is a tool for getting what one wants.
I think what the OP wants is to know he isn't just the funding agency of her entertainment. I think she wants to know he can be generous.
I think Vash once mentioned (which I agree with), is that couples with different income levels should *agree* on how to pay for things. If the couple wants something that the 'poorer' partner can't afford, then s/he needs to say so. Then, it becomes an issue of 1. finding a different thing, 2. the 'richer' partner *choosing* to pay more. 100% willingly, with the other partner accepting 100% willingly. Its when there is a discrepancy that trouble arises.
Personally, I'm *not* comfortable with a partner paying for everything. From my own experience, this leads to power issues. Generosity in giving, and receiving, is one thing. Dependence, which is the slippery slope the OPs gal is on, is another. And forced generosity is, of course, not generosity at all. These two are not compatible.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh