Could you consider working on a budget together so she visually "sees" the money better? Something you YNAB (You Need a Budget) or even just a handwritten one so she sees the income and then where it goes every month?

Maybe a quick finance class you could both take together would work, too, if both were willing.

Some people deal better seeing cash in hand than keeping track of invisible numbers, if that's the case with her (which is partially what I'm thinking based on what you said) - maybe pulling out cash for spending extra fluff items would be helpful for her. Or a joint account you both put your share into every two weeks/once a month so that you aren't paying the lion share for everything and can also save up.