There are many different reasons for failed marriages. To add here all those I have observed would be quite long and still not exhaustive.
For one, people today are poorly prepared for marriage. Living with someone of opposite gender is a challenge, and this is not being addressed by yeshivos or Bais Yaakovs at all. No skills in communication, no understanding of the obstacles, no guidance in setting up homes, no training on how to assume and share the tasks of managing a home or family.
Secondly, the guidance that young couples seek is fraught with problems. Some seek guidance and direction from roshei yeshivos or kolellim, others from sundry other rabbanim, chosson and kallah teachers, most with great intentions but zero understanding about how to assist a struggling relationship. Others approach family members whose biases cannot be excluded. Such people, again with the best intentions, tend to make a bigger mess of things.
Thirdly, no one is prepared to deal with conflict. Yes, husbands will argue with their wives. But nearly any issue can be resolved if the two want it. But many take conflict as basis for battle, and engage in countless ways to destroy the other. Once this begins, it becomes almost impossible to reverse it and create a harmonious relationship.
Next, there is often a huge difference in personal beliefs and the importance of various issues. For example, some young people will consider their “right” to be by their parents for Yom Tov sacrosanct, being violated if the spouse insists on different. Some girls have been taught to be their husband’s mashgiach, and they are offended deeply if he sleeps late in the morning.
On and on, this list can go. We can introduce the uses and abuses of technology, incessant phone use, secrets, etc. Some of these are introductions of the current generation.
Meanwhile, there is an alarming increase in failed marriages. Maybe we need to address the ways in which we can prepare young people for marriage, and then help them maintain them.