It's that simple really. Consider the way people used to marry before the s8xual revolution. For a man of a good standing in society it went on like this: he meets a girl, usually while visiting family or through friends, or it could be a neighbour's daughter. They spend some time getting acquainted with each other. Then they start courting, meet each other's family and learn each other's antecedents.
They mostly belong to the same social class and know what sort of behaviour is considered acceptable in their circles and what to expect. After they marry, they assume clearly defined roles: the husband is the head of the family, the protector and the provider, the woman is the wife, mother and homemaker. If she had not been married before, she is expected to be a virgin before the wedding and keep chastity after, and not to leave her husband under the punishment of divorce which is considered a dishonour to her and her family. He also can divorce her if she refuses him his "marital rights".
The way people marry nowadays is quite different. It mostly goes like this: boy meets girl somewhere in a night club where they both get drunk and end up in bed with each other. Next morning they get acquainted and if the s8x was good decide to have another date. Eventually they move together and after a certain time, depending on her age, the girl gets a case of what some call "baby rabies" and "forgets" to take the pill one day. Pregnancy ensues. If they have middle class pretensions they'll marry before the child is born, but marry they will.
After the first excitement is over, they both realise that their past life is gone and that children actually need constant attention and don't raise themselves so they can't just drop them somewhere and go get plastered with their friends. It's probably the 1st time they will try their hand at housekeeping, either, with little success because none of them were taught it. Neither is good with finances and there is also some debt. The guy is probably a lousy breadwinner and his wife could't cook to save her life and tries to boss him around and make him do most of childcare, too. He knew she was bossy before but put up with it because s8x was good but now she has no interest in it any more.
Add to this that our culture views divorce as empowerment instead of something shameful and you know the rest.
So which one of these models leads to a stable family and which one to the divorce court. You decide!