A man lives in a small village. His whole life he knows all of his neighbors. There are 5 girls in the village around his age that he could marry. Everyone gets married and stays married. It is the culture, and the lifestyle of the country requires the man and woman to depend on each other. He has a relatively simple choice (ie to chose 1 of 5 women). He finds 3 attractive enough, and 2 are good enough personality. Hopefully one of those 2 girls will like him and they will get married. When he does, he is content, he has the best wife he could expect to get. There is no need to "look for other women", and the marriage is very important to him and the family.
Now, if he get' a better paying job in the city two things happen:
1) He is more independent of his wife’s help (ie. he could hire a made)
2) He is exposed to MANY MANY more woman. More beautiful, more ....
So it is natural that many stable marriages fall apart in this setting. Even more when the woman can work.
This is what has happened in the US. Now marriage is no longer part of the culture. Most people there don't bother to get married unless they are going to have kids. Very few of my friends are having kids, and even fewer are married. I am also like this. For me there is no point to get married, unless I have kids. Then I do not trust a US woman (or any woman exposed to the same situation). If I got married it would be with a woman from a culture where the marriage was important and I would stay that way, ie. married.