Well, she is not going to spend a lot on clothes and jewelry I am sure. Response time will be short too. Don't know about lovers though, might be a problem sometimes. Hope he likes children, I mean puppies. I mean childpies. I don't know what I mean.
Are they thinking about adopting? Wait what would they be adopting? Is it moral to adopt a kid if your dog is your wife? They might have to be safe and just adopt a dog. The kid situation seems like it could cause a problem.
I remember a few years ago there was a minor internet s***storm over some guy who posted to a polyamory community talking about problems he was having between his "wife" and his "girlfriend". People started giving him serious suggestions, but eventually it was revealed that his "wife" was a horse. (The "girlfriend" was human and god only knows what kind of person is willing to play second fiddle to a horse - a pretty messed up one I would think.) Apparently he used to roll his you-know-what in honey and oats to get her to perform her conjugal duties. One can only hope she got a little too enthusiastic one day and bit it off.