... in Canada according to a study based on the 2006 census. Here's the report: http://www.cbc.ca/consumer/story/2010/10/04/vanier-study004.html

There are some problems with the study - they count everyone 15 and over when the legal age for marriage is 16 (and that's extremely rare - I believe you still require parental consent until 18 but don't quote me on that). What disturbed me the most was the little box at the side:

Top 8 reasons why people marry
Feeling that marriage signifies commitment
Moral values
Belief that children should have married parents
It is the natural thing to do
Financial security
Religious beliefs
Pressure from family
Pressure from friends
Top 5 reasons why couples separate or divorce
Different values and interests
Abuse physical and emotional
Alcohol and drugs
Career-related conflict
Source: Vanier Institute of the Family

I can't beleive infidelity is #4 on top reasons for divorce. I suspect a good proportion of divorces due to differing values, abuse (especially emotional) and even alcohol and drugs involve infidelity. In fact I'm pretty sure that "differing values" is code for one spouse thinks it's ok to cheat. Even career-related conflict is probably predominated by infidelity - if one can't screw the boss how is one supposed to get a promotion?

Anyway, I thought I would post it here in case anyone is interested. Some of the comments at the bottom are pretty funny. Some are very sad. But some are encouraging as well.