Wow, I can't help but laugh a little at this post (very good-naturedly, I promise!) ...
I'm a female bassist, but I also have a wife. Yep, we both came down with lesbianism, likely in the womb so far as we can determine. Anyway, she's a big supporter of my music, though she's not herself a musician. Basically, we just talk about things, like if I want or need some new equipment that's above "personal money" levels, we just have a discussion and see if it fits in the budget. If not, sometimes I'll sell something to raise money for the purchase, sometimes I'll put it on a card after discussing a repayment plan with her, and sometimes I'll wait and save up a bit. We do the same with the things that interest her.
The relationship trouble friends of mine, both male and female, have gotten into with purchases musical and otherwise are when things are done "sneakily," or hidden from a partner. That's basically lying to someone you supposedly love and respect above all others. If I were in a relationship with someone where I truly had to lie and hide things from them in order to pursue something that feeds my soul the way music does, well, I'd not be in that relationship for much longer once I discovered that fact. Communication is key in relationships, it really is, and if I can't communicate with a partner about what I need and the things that make me happy and fulfilled, I'll be looking elsewhere really quickly.
That's my take, anyway. Oh, and the above is definitely not in any way meant to discount or criticize anyone else's feelings or experiences with basses and wives.