I think we'd agree that a country that has laws framed around the notion of 'concubinage' is coming from a somewhat different cultural perspective that ours.
If you can't obey the laws of the country you are in, then you tend to be in line for the punishments that accompany those laws.
To be fair, Andy, if I were to go a country that is perceived to be as laissez-faire about sex as that country is it would not occur to me to check on the legalities on having a bit on the side.