Well, just like if you had children , its a package deal!!
Im sure he loves them I mean who couldn't love a little yorkie.
Maybe you could buy one of these and keep it in his closet, garage or under his bed, at least its out of the way and if you want to go to his house you will already have their beds there. With this play yard they can still be with you but confined so they wont pee in his house when you cant watch them.
Id even buy and extra bag of food and put it in a tupperware container at his house for the " just incase you stay there moments" .
Also you might want to say to him , what you just said to us.
That your dogs mean the world to you and you hope they don't ruin what could be a great relationship
Amazon.com: Doggie Crates - Pet Travel, Indoor or...