I understand the struggles, but dont try to make all your interest her interest. Great marriage partners are not "shared interest friends". Personally I think the best marriage partners are where there are complimentary differences. You should bolster her weaknesses and vice-versa. Its great, but completely unnecessary that you have lots of shared interest.

Furthermore, your kids are 1000x more important than this.

It sounds like the root of this issue is that (a) She is not working which you feel resentful over, plus (b) You are actively trying to better your families situation and she is telling you that you're wasting money.

Frankly if she isn't earning and your kids are being taken care of, I don't think she gets a say in the matter. She can voice her opinion and you should consider it, but you are under no requirement to follow her wishes. Just like you probably don't get a say in certain aspects of the house situation / kids rearing that is her primary responsibility.

Thinking of marriage as a "Joint Venture" (ie. Raising Kids, Inc) is less romantic, but more practical way of looking at marriage. You are in charge of certain aspects of this joint venture and she is in charge of certain aspects...you both need to respect each other and support where you can. This is what the marriage contract is all about....