Marriage, in its essence, is a partnership between a man and a woman in order to enable physically, financially and emotionally safe environment to children to develop in. It allows the men to transfer his resources from competing over women to raising his children.
Fifty years ago, divorce was very rare and thus a man, or a woman, could make huge sacrifices for their families. However, since divorce today is so common, both parties must take caution and protect their individual interests more, and thus the family interests less. Therefore, the popularity of divorce affect intact families.