but I'm struggling with what to do with it. Feels like another hill on the roller coaster of DBing, we were at bottom of hill and now W thinks it's ok to talk and act pleasant again.
That's pretty simple, you do nothing. Celebrate it internally as a baby step, but keep the distance/ pursuit dynamic in mind. If you make any move towards her she'll go right back to distancing. I'm sure you've read the squirrel-feeding analogy, just remember if you do anything other than hold still and let her approach that she will go running right back up the tree and it starts all over again.
