ZB, this is one of those places where the comparison with alcohol is a good one. It does indeed hurt to know that your partner, given a choice between you and a six-pack, would choose the six-pack. And asking them NOT to drink the booze is just an exercise in futility. Until they decide not to do it, you're just wasting your time.
You might consider attending alanon just for the peace it gives to you hear how other people deal with the issues of living with someone who places them low on the priority list. Alanon is all about GAL, especially spiritually. It's free and convenient, and you never have to say one word out loud.
Your W's sitch sounds very much like Lou's BB and her shopping.
Going out and getting the puppy after you specifically asked her not to-- wow! It does show a lack of respect, but in a backhanded way, it also shows how much she trusts you-- that you will not walk away or hurt her when she defies you. I've been in situations where I didn't defy my partner (and I never defied my parents, not even once) because I was afraid of them. Of course, flipside way of looking at that is that she really takes you for granted. Taking you for granted is preferable to walking on eggshells around you, but there should be a happy medium.
Bringing in more and more animals certainly does reduce the care that you're able to give each one. Kind of reminds me of Mia Farrow and all those children she adopted... she wound up not being able to keep an eye on all of them...