PP,

I would respond:

"I think it's important that we focus on having some individual time with the dog. As you can imagine, we both love the dog very much. I propose that we come up with a fairly equitable schedule. I would like to pick up the dog and keep him with me for 1 week and then drop him off with you for the next two to three weeks? Naturally, we would ensure that food, toys and other comforts are packed for him. Thoughts? Thanks- PP."