There is a low divorce rate and families are usually invested in supporting the couple.
Usually you know the family you marry into or you are related to them. They are not strangers. Sometimes they are nice and easier to get along with because they already know you and they have chosen to have you in their family.
Family members can be loyal.
Just because the divorce rate is low, doesn't mean the marriage is happy. In an arranged marriage just as the family can support a couple they can pressure the couple to stay together.
Even if you are related to the family you marry into they can be nasty.
The effects of marrying between families, for example two or more brothers from one family marry two or more sisters from another family.... if one marriage is having problems then it will definitey affect the other couple. Even if theirs was working. It's hard when your husband's brother is treating your sister so badly You want to defend your sister, but your husband defends his brother. This can destroy your own marriage.
I know a boy who was 17 years old and married to a woman who was 25. He wanted to marry somebody else. He has a son but no love in his life.