Relationships of any nature need this indelible quality called Empathy. In simple words it means to understand the perspective of other person. It is Empathy that enables us to be less judgmental of other people. It is also explained as "the nature of seeing the world through gentler eyes".
We all have relationships - with family members, friends, colleagues, society in general and the world in large. Most of them are sustained based on this particular quality. The fact that we are able to sustain some such relationships in our life means that we are all Empathetic to some extent. We are all humans, so we also tend to lose it few times and that explains the reason for volatility in some of our relationships.
We need it the most when a conflict of opinion rises in a relationship. A conflict need not be some sort of an ugly war and a conflict need not be between a good person and a bad person or between a good intention and a bad intention. Conflict only means a difference of opinion. In this world smart, well-intention-ed, good nature people have conflict with each other. One person need not have ill intent, or be evil or crazy to have a conflict. Good people have conflicts with good people. What helps us reconcile those conflicts, what allows us to have better relationships at all levels – with society or in a family is Empathy.
In such conflicts what matters the most is how much we understand the people on the other side. It might be a scenario where the other person might seem to have a fundamentally different opinion but that doesn't mean they are crazy or bad or out to get us. It only means that they had seen the world in a fundamentally different way through their upbringing and experiences. When we fail to look beyond the people we know or the patterns we had seen in our past that is when we fail to understand the other person.
It might not be specific to a generation or a person, but rather to a context or certain personality that causes us to NOT understand the lack of empathy in us while being in a relationship. Especially when we deal with people who are emotionally very close to us we tend to lose our sense of empathy. It happens unconsciously and it becomes difficult to realize this. When we begin our conversations we usually start on a balanced tone with an intention to share our perspective, make a good point and simultaneously try to understand the other person's point of view. Then things begin to spiral out of control. Sometimes we end the conversation with anger and lack of any patience or any desire to understand the reasons for anger in us/other person. We fail to realize that things we said in such anger might not be the right things to say in such moments. We also fail to put any further efforts to understand why the other person sees the world so differently than we do.
Why do we tend to act like that?
I learned that we tend to easily lose our sense of empathy when we deal with two kinds of people - those we like and those we hate. It is easy to see that we don't try to understand the people we hate. In case of people we like the most we typically lose our empathy and it causes us to sometimes behave the worst with the people we care the most about. This happens because we feel the pain when the people closest to us fail to understand us. It doesn't hurt when a stranger misunderstands us because we don't care for such opinions. When somebody close to us doesn't understand us, seems to be judging us then our defenses go up very high. It makes us emotional about it and could at times hurt us. In such a state of mind it is not easy to take a step back, think and try to take the perspective of the other person.
Another reason for such behavior is our approach in dealing with people in such close relationships. Mostly we fail to see the other person changing in a relationship. People who care about the other person grow in a relationship. They grow to be more empathetic, more compatible and more caring. It is such changes that we fail to notice. We fail to notice such changes because we unconsciously get into a certain routine in any relationship - like with your brother or sister or friends or colleagues. Such a routine makes us to think in a certain pattern. As a result we don't update ourselves often enough as the other person is changing themselves from who they were to begin with. As an example - your sister or brother would seem the same kind of person to you but if you ask them whether they are the same person that they were 5 or 10 years ago in this relationship with you then the answer would be different. They would've grown more concerned (or may be less concerned about you), become more matured in understanding you and things like that. We don't see such changes in other people. We judge them as they previously were. We have to get better at updating and notice that when other people are trying to evolve, change and trying to be better we need to stop using the same arguments that we used with them in the past. We cannot use the same judgments and same reasons as this person is now evolved in life and relationship.
Not that I am an expert but I learned these reasons and clearly observed the patterns of such behavior in a relationship. These concepts are simple but simple doesn't make them easy. Such qualities are easily developed through experience and an intention to understand people better.