Wife: advantage or drawback when asking for visiting student position? My wife and I are both PhD candidate in major-but-not-elite French universities. We study in completely different fields.

She got a visiting student position in the US for 1 semester as of January 2017. I would also like to go to the US as visiting student, at the same time,  for both personal (i.e. not being one ocean away from her during 6 months) and professional reasons (i.e. experiencing the anglo-saxon scientific research paradigm, international experience, etc.).

Question: When contacting Professors of local universities, should I mention that my wife will be in the US at the same time, or not? In other words, would P.I.s be more prone to accept me as visiting student (I'm financially autonomous, so I'm not asking for a funding) if they know my wife will be there (because of empathy or whatever), or would they tend to consider that I apply because of my wife, and not because of the research -- so that I'm not motivated enough?



Edit: As given answers made me figure out, a motive of my question is that there is no research team in the US that study my particular sub-field. So the question "why are you asking for a position in our lab, since this other lab in the UK is closer of your research topic?" might be raised.
Be honest. Present it as a happy coincidence. That's what it is, after all. For example,


  I've always been interested in different research communities and paradigms, given how this knowledge can help me to work more effectively with others and to introspect my own methodology. My wife has been offered a place in [state] also, so this is a ideal opportunity in my academic career to gain the experience I've sought.