I'm doubtful that he would be so stupid as to vote for something which would put his wife's future in the country in jeopardy .. I kinda assumed she had citizenship. If not then sure it's understandable, but you'd expect that to be mentioned in the interview?
The way it's headlined you assume the issue is a political decision dividing them, which I would be pretty doubtful of. It seems more than a little outlandish that this alone would destroy a happy marriage, especially considering they must have discussed politics before. Sounds to me like this guys marriage failed, and this was something which sparked an argument and he's using that to make a story. I reckon if you talked to the wife she'd have a bit more to say about why she left.