There is a saying that it takes a village to raise a child. I would say it is equally true with marriages. Too often marriages end up building walls within social networks. Some statistics show that the longest lasting marriages have the most guests (but also the least expensive). When people lived in villages and small communities, societal norms play a more important role than in the anonymity of large cities. I am not saying that infidelity, spousal abuse do not exist in these social situations but that people tend to be influenced by models of good behaviour in these settings.
Another thing that I would say affect marriages are that finances play a major role in much of the stress that couples experience. Families want better things. Men focus on their careers in order to improve their finances. Women do not like to be neglected - most people like to have reassurances that they are loved and respected in a relationship. They tend to express their frustration at the neglect (because the man is too busy) by exhibiting attention seeking behaviour (nagging and arguing in some cases). This makes home life less bearable for men so they spend even more time at work. The problem really is not a specific problem in the relationship but a failure to communicate properly and to establish common goals.
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