I have been watching Riley and Rosie's interactions closely, and I'm coming to think that his growls are, for the most part, growls to keep her in line, not growls that might turn into an attack. They are playing more. He goes into the play bow with her a couple of times a day now. And you know what? I think that my boy has been lonely. Other than the occasional Patches visit, he has not had anyone to play with for quite some time; Boscoe was not much for playing the last few years.
This morning we slept in until 6:30. It was glorious. Yes, I let Rosie out at 2 a.m., and yes, Doug let her out again at 5, but after that we all went back to sleep. Oh, God, it felt good.
At 6:30 I put Rosie and Riley out back and went in the house to get a stuffed squirrel for her to play with (so that she wouldn't chew on my arms and sleeves). But who wanted to play with it? Riley did!
So he and I played tug of war while Rosie dug another unauthorized hole, and then he raced around the yard with the squirrel in his mouth and Rosie chased him like mad, occasionally getting so far behind that she would sit down and wait for him to thunder past again, occasionally tumbling over a clod of dirt and rolling down what I think of as a bump in the yard and she must think of as a hill.
Things are not perfect. He still growls at her, a lot, in the house. Sometimes I can figure out why (she approaches his den under the table, or when he is eating a treat) and sometimes I can't; the growls seem to be triggered by nothing more than her presence in his general vicinity.
We try to avoid being all together in a very small space (which makes breakfast on the porch more difficult), and we still watch them closely and don't leave them alone together, but I think that this relationship is going to work out after all. I think when she gets a little bigger, and a little less chewy, and a little less bouncy, Riley is really going to love having a friend.