One of those studys that seems to point out the obvious, discussed in this article.
One of the discussion points missing here, although might be included in the study itself (I haven't had a chance to check), is that joining the website in the first place is likely to be indicative of the marriage falling apart. If you have to seek sexual thrills outside of the relationship, whether in the form of fantasies or by physically cheating on a partner, then there is a fundamental flaw in the relationship in the first place. So the data is not at all surprising. I would point out that the population the data is taken from is rather skewed in favour of those who may cheat, considering the site they are on.
Skeptical kinkster musing on whatever takes my fancy!