I agree with not seeing the same things in the same cards even in a particular common situation...though if the question is: does he have another woman etc. and the Empress pops up, I would be pretty certain that he does...or an all-too present Mother (which is really the same thing, I guess). I would more see the Queen of Pentacles as the Wife, like someone said, the keeper of the family hearth etc. I guess she could be the other woman in the sense that she is "keeping the fires of love banked" until her lover returns. But that brings us back to what most of the others were saying, two cards can come up together in the same question/situation and it means different things.
Example: The two cards you mention come up, in one instance it means exactly what you said at first, and the very next time it comes up in that situation, it now means the Queen of Wands is the only woman (there is no other) but she has a very intense energy that is intimidating her husband/lover and he wishes she was more of a sedate woman with a more controllable or defined energy - perhaps more of a homebody literally or metaphorically. Now, that could lead to him having the wandering eye and then following the eye all the way (perhaps to the Empress) but at the time of the reading it could mean he's insecure and can't talk about it because he's scared but if she knew she could address it with him and that is the message that you are being asked to convey. In other words, there might be a battle or clash ensuing but it might not be literal.
But I say, if it always comes up that way for you and you can confirm it every time, then stay with that until, and if you find that it's starting to mean something else.