If there is a need to be frugal ($700 a week seems like plenty to me), maybe consider going to a financial counselor or financial planner with her. Prior to marriage, I think it’s a good idea for couples to meet with not only a mental health counselor, but also a financial counselor, to determine acceptable patterns of spending and lay all the cards on the table, so to speak.
For the sake of shalom bayit, I’d separate household expenses from personal expenses. For instance, allocate funds for groceries (make a shopping list every week), utilities, mortgage/rent, dry cleaning/reasonably-priced clothing, health and beauty aids, work-related expenses, Gas/MetroCard, etc. Once you’ve taken care of your necessities, than you can put remaining funds in another account for discretionary spending.