I was thinking this could be thought of the 2nd photo in a series (with potentially more photos in future years), so there could be some connection to the first one.
I like that the man and dog are looking at each other and the man is holding the dog's paw. But yet you want the couple to look like a couple.
What about them seated next to each other and facing toward each other at a 45 degree angle (so some distance between them to allow for that), with knees touching. Then each one's dog next to the other person's leg that is closest to the camera, but facing their person at about the same angle; then each reaching across to hold their dog's paw with the person and their dog looking at each other, so the adults's arms criss cross. (I can picure it but can't describe it well!) So there's a connection between each adult and their dog as well as a connection between the couple.
edit - I was thinking if using a love seat or something simiar, what about wicker or some type of patio furniture that looks believeable outdoors?