I sympathize with you on the argument with your friend. People seem to naturally make issues bipolar, for or against, and taking a third position is incredibly difficult. Whenever I try it, invariably somebody conflates my position with one of the poles.

FWIW I agree with everything you've said here. I also did not read the bit about the husband's spending as the central issue since it's half a sentence, which the LW throws on the mounting heap of reasons why she should be able to trample an important boundary. If there is an imbalance in LW and husband's financial freedom, that's a significant but separate problem from the dog.