People have a flippant attitude toward many things, marriage included.
Sure - well then we shouldn't be surprised to see lots of adultery since most people don't know what marriage really is at its core and have no understanding of what it takes to protect the marriage and make it secure by actions they need to take both before and after they get married. Since there is virtually no understanding on that front, the article's point that adultery is really bad and hurts people (and thus people simply shouldn't go there) is mostly pointless.