of course that in this crazy world we live in the mere fact of travelling with your GF/wife that doesn't have residence in country 'x' along with BF/husband who is a citizen of 'x' can result in 'we suspect that you are trying to sneak in and stay!', in fact I know a Canadian guy who was accused of that very thing in Canada.
I know of cases at the U.S. border where U.S. citizen couples were separated and given the fifth degree, put in separate rooms, accused of illegal acts, and in general harassed, simply because the CPB agent suspected something on the basis of the place of birth appearing in the US passport. I also know of situations in this post 9/11 world where long-time visitors to the U.S. were subjected to "special" screening simply because their passport reflected birth in a communist country.
For these reasons, I approach CBP with the view that most of the time everything will go well, but that some times it may not, and I, therefore, measure my words and actions carefully, as arguing with armed law enforcement officers is not something to be undertaken lightly.