I don't get that you're not a fan of his wife, just that if you weren't dating him, you wouldn't have reason to hang out with his wife unless you happened to be coworkers or something.
I've been having some talks about this subject myself lately. Perhaps if you ask him if his wife has a friend that he likes well enough but doesn't have anything in common with - does he feel obliged to hang out with both of them and be her friend just because his wife likes her? Not sure if his wife dates, but if she dated somebody who's a vegetarian golfer and he's a carnivorous football lover, isn't it enough that he likes and respects the guy, does he feel he should hang out with somebody he doesn't feel a good friendship with just because his wife would like it?
I'd just probably reiterate to him that I think shes a wonderful person and I don't mind being around her at ALL, but that Id be doing a disservice to everybody trying to force a good friendship when there just isn't the basis for one.
Happiness will never come to those who fail to appreciate what they already have.